Rapid Prototyping and model accessory design


There has been a lot of buzz lately surrounding Rapid Prototyping, or as it’s commonly called: “3D printing”, in the modeling community. While it’s true that it is an exciting technology, we’re still a very long technological journey away from practical and affordable applications for the average modeler. The day you can take your Iphone21 S into your local museum, scan that FW-190 and print out a model kit on your Mr. Make-a-Part 2000 is still a long way away. Oh well – what’s the harm in dreaming? It’s the dream that inspires…

There are, however, many practical applications for 3D printing technology today. One of these applications is the creation of masters for aftermarket resin accessories. Companies like Eduard (for their Brassin range) Aires, DEF Models, Live Resin, HAD Models, Falcons Bench and many more, are seeing the value in creating models in CAD software and using those models to have masters printed. But creating these models is not as simple as scanning the real item and punching the scale into a computer. There’s still no “make model” button. It takes experience and skill to design a scale model for printing, one which has value beyond just holding something “neat” in your hand.

As a daily CAD user, I’ve developed the “flow” and practices that allow me to quickly break down complex shapes and surfaces to create a plan for modelling them efficiently, and the skills to put that plan into action in various software packages. As a modeler and a product designer, I can look at a part and evaluate what a user is likely to want or expect in a product. As an industrial designer and former production machinist (who also happens to have done a lot of resin casting), I’ve developed the ability to look at a part and see it in terms of a production process. As someone with a full-time job and little time for my hobby, let alone a cottage industry aftermarket business, I know that efficiency is something that MUST be designed into the production process at every opportunity if the effort is to remain sustainable and enjoyable over the long run.

So when an aftermarket company approached me and expressed an interest in having some very small detail parts modeled in CAD and printed for the purpose of using those prints as masters for casting, I knew that I could leverage my skills and background against the new technology to help this company bring their product to market as efficiently as possible while creating a high quality product for the end user, the modeler.

The first step was to define the end goal – the deliverable:

Masters for resin casting 1:35 scale Leopard tank mantlet plugs for the Leopard 1 and 2 (2 types of plugs)
8 plugs per vehicle.

1:1 mantlet plug

Easy! But let’s look at it through the perspective of the company who would be offering these pieces.
They would need to select a casting vendor (or plan on casting them themselves) and have the parts cast. We’re talking about some pretty tiny parts: less than 2MM in diameter with details less than .25MM thick! The design of the parts should facilitate easy handling for the caster, packaging, and the modeler. It was an easy decision to design a “sprue” arrangement to hold the part and make casting and handling easier. I figured that it would be a negligible amount of added print time, material, and casting resin to extend the sprue enough to add 2 spares of these tiny parts to the sprue as one of these parts from each set was bound to be sacrificed to the “carpet monster”. OK, so now we had a sprue, or more accurately a casting block, that was about 30MM long and still only about 3MM wide. That’s hardly enough to mix a batch of resin, and mixing that small of a batch is likely to end up with an “off” mixing ratio, leading to uncured, wasted material and time. Casters typically overcome this problem with small molds by making “gang” molds. These are molds that produce multiple copies of an item with each casting cycle. This is done by making one mold of the original part, casting multiple copies, then making a mold of those parts that will create multiple copies of the item with each pour. Often detail is lost, shrinkage accumulates, and the product suffers. Overcoming the need for this multiple generation process is a perfect application for CAD and 3D printing! In CAD it’s a simple matter to pattern a feature or a body to create a “gang” master. I figured that if the caster could get 10 blocks of parts per pour, an economy of scale would be established immediately. After the main block is removed from the mold, the individual blocks could be snapped off of the “gang” block and dropped into packaging. All that was left was to add an additional bit of length so I could add a product number to each block, elevating the perceived level of quality, and we’d be ready to upload the file to the print bureau.

early block ideation
single block

I uploaded the file and sent a link to the aftermarket producer letting him know how to order his prints. I also uploaded the STL file (necessary for printing) and another common type of CAD file (for his archiving in the event of future work CAD needs) to DROPBOX and sent him the link to the files. At that time, I ordered an archival print for my own use. My part showed up a week later and it looked fantastic! It’s really amazing what the new SLA and SLS machines can do. Be aware that some finishing is still usually required to get smooth surfaces on the masters. A little knowledge and a good working relationship with the print bureau can help minimize the amount of work required to prep the prints for casting.

While 3D printing might not yet have reached full maturity, where a modeler just has to hit the magical “make part” button (don’t forget, I’ve only addressed the CAD model side of the equation – I haven’t even touched on the skills required to successfully operate a 3D printer) there are still some great applications for the technology, and advances in affordability, fidelity and ease of use are constantly being made. Who knows – it may not be long before you’ll have to look at your stash shelf to see if you have room before you hit that button again!


The Leopard 1 and Leopard 2 Mantlet plugs will be available soon from LeopardClub http://www.leopardclub.info
They will include photoetched retainer chains.

I can be contacted at Peterjhamann@gmail.com , or https://www.facebook.com/PeterHamannModelServices


AEROBONUS 1:48 scale US NAVY Triple Ejector Rack TER-7 (A/A37B-5) and Multiple Ejector Rack MER-7 (A/A37B-6)

An airplane has found it’s way onto my desk!

Specifically Hasegawa’s 1:48 scale A-4E Skyhawk. Hasegawa produces some of the finest detailed and best fitting kits available, and the Skyhawk is definitely one of the cleanest-building, most well-detailed kits, out-of-the box, that I’ve ever had the pleasure of building. One thing it is lacking, as are almost all Hasegawa kits, is ordnance options. The kit includes auxiliary fuel tanks (drop tanks) and Skyhawk specific pylons, but no weapons or weapon racks, so aftermarket is a necessity if you want to hang anything that goes “BOOM”!

Fortunately Aires of the Czech Republic offers a solution. This prolific aftermarket company exploded onto the scene in 1995 with their first resin aircraft detail set for the Hasegawa Ju-87 Stuka. Since then they have continued to introduce new products at an astounding rate. Beginning with cockpit and engine sets, and later expanding into other areas, it seems that now there is no area of aircraft detail that remains unattended to by Aires. Recently they have begun to offer a line of more tightly focused detail items to help modelers fill in the “gaps” in their models and dioramas with items like seated and standing pilots, ordnance, airfield equipment, and pylons and racks. These items appear under the AEROBONUS name and are well worth a look.

Let’s take a look at 2 of these items:

AEROBONUS 1:48 scale US NAVY Triple Ejector Rack TER-7 (A/A37B-5)
AEROBONUS 1:48 scale US NAVY Multiple Ejector Rack MER-7 (A/A37B-6)

Cast in Aires typical grey polyurethane resin with excellent, well-cast detail…well really what else can I say? I don’t have measurements of the full scale articles, so I can’t comment on dimensional accuracy…wait wait! I hear you saying “Well then what is the point of a REVIEW if you don’t know if they’re accurate or not!?” Well dear reader, my intention is not to review the items in question. My desire is to share detailed pictures of what you get for your money. I’ll gladly let the discussion of accuracy take place in the nether-holes of the interwebs. Those places where experts roam unconstrained by human relations to freely engage in heated exchanges of opinion about such pressing matters as fractions of millimeters and thousandths of an inch.

Was that snarky? I’m sorry. Truly, I am. OK here are the numbers:

Actual product measurements:
LOA (length overall): 81.17MM / 3.196″
Width of the main housing: 4.25MM / .167″

OK – Pictures are way more fun!


The basics



Side-by-side with the Revell rendering of the same item.


OK there ya go!

The modeler will need to add the short cable that runs from the AFT face of the ejector assembly to the main housing. Aires / AEROBONUS have provided a small indentation at the places where the modeler would drill a hole to add this – a nice touch!

These things look great and are very well detailed. I can’t wait to add them to my A-4.


Dave Roof – Retired Marine Ordnanceman, owner of Flying Leathernecks Decals http://flyingleathernecksmodels.com/ and “Awesomerest guy ever!™” sent along these photos of a MER-7 with an A-6 Intruder attached to it. Thanks Dave! You can see in the pictures that the nose contours on this MER-7 are soft and rounded.

So out came the sanding sticks and within a few minutes I had something that more closely resembled what I saw in Dave’s photos, as well as being closer to the Revell example.
Top – original AEROBONUS part
Center – Modified AEROBONUS part
Bottom – Revell part

It didn’t take long to do, and renders it a vast improvement over the Revell part in terms of detail. That being said, I think I would be happier if the nose on the AEROBONUS item were a bit “fatter”

OK well it turned into a bit of a proper interwebs review in the end, but I’m OK with that. If what I’ve posted helps the reader decide if the item is something that they want to add to the stash, I’ve done my job.

Dave was kind enough to permit me to post his additional photos, so here they are.














An upgrade for the ASU-85

One of the things that has always bugged me about my ASU-85 has been the total lack of detail on the interior of the crew hatches. Even though eventually I’ll add a seated Soviet tanker, which will help hide the smooth flat surface, I’ve decided to add some detail to help liven the area up a bit. I’ve also decided to try to attend the IPMS Madrid show in Mid-March (in a week and a half!) and since this is the only model I’ve completed in the 12 months since last years show, and thus, the only thing I’ll have to put on the tables, I’d better get cracking!

I looked for reference photos online and couldn’t find any. Sometimes this can be a good thing, as it (hopefully) means that no-one else can either, so the odds of someone pointing out an inaccuracy are minimal.

I started by planning the general layout of the detail and decided on a rim or gasket-like appearance, with a few fasteners and the suggestion of a handle and latching mechanism. Once I had the idea in mind it was time to get busy. My goal here was to try to complete the rework (minus paint and weathering) in one build session. I also wanted to leave the exterior of the hatch undisturbed since painting and weathering had been previously completed.


I started by tracing the hatch with a .5MM mechanical pencil.




Then I scanned the tracing and opened it in Adobe Illustrator.


I offset the scanned lines 2.5MM to the inside to account for the thickness of the pencil lead…


then measured the kit hatch to confirm that the Illustrator drawing was sized correctly compared to the kit part.


I then added the gasket width and a few other features…


copied the pattern a few times and printed it out onto plain paper. Here you can see the kit hatch laying on the print to confirm the size.


I attached the pattern to some .010 sheet styrene using double-sided tape.


I started by punching out the inside corners with my new RP TOOLZ round punch and die (2MM diameter).


And cut away the rest of the interior contours. Then it was just a matter of squaring everything up with a file and adding some details with styrene strip, punched bolt heads, stretched sprue and some thinly sliced styrene extrusions.



I think that the new hatch is a huge improvement over the original featureless kit part.


The whole process took a little bit over an hour and was well worth the time, in my opinion. Now to see if I can get it painted in time…

Stay tuned!

RP TOOLZ hexagonal punch and die set

Well it’s been quite a while since I’ve posted anything, but a new year (is it really March already?) and a renewed commitment to my modelling work has brought me back around to my passion – making stuff!
A large component of the process of model making is of course – TOOLS! I have been in a bit of a gear-acquisition mode lately, seeking to expand my capabilities through the purchase of equipment and software that provide me with a greater variety of solutions to common modeling problems. One of these problems being: how to add nut, washer, rivet and bolt head details to a model. In the past, I’ve relied on the incredible Grandt Line Products (http://www.grandtline.com/) series of injection-molded nut, washer, rivet and bolt head details to accomplish this.



Sadly, my stock of Grandt Line products is nearly depleted. Ordering them online is tough, because I really feel like I need to see them in person to select the right size and style for what I’m doing. If you happen to be one of the fortunate but shrinking group of modelers who have a local hobby shop that has a good selection of Grandt Line products, consider yourself very fortunate!

I also find them a little hard to use sometimes. Cutting them from the sprue can be tricky, often resulting in a tiny burr that can prevent them from sitting flat on a surface. You can overcome this by snipping them from the sprue and leaving a portion of the “stem” that can be inserted into a pre-drilled hole. This can be useful because it allows you to lay out the fastener pattern ahead of time with a pencil, then run a pounce wheel along the line to establish the spacing before you drill the holes. The problem with this method is that the stems are sometimes off-center from the center of the nut / washer detail, and if you don’t get all of the nut / washers rotated to the same orientation, you can easily end up with a wavy line. Aside from that comes the age-old problem of never having just the size and style that you need, when you need it! What to do, what to do?

Enter RP TOOLZ punch and die sets!

RP TOOLZ of Hungary has designed and produced a set of punch and die sets for both hexagonal and round shapes. They can be used to produce positive shapes (discs and hex shaped pieces of plastic) in various sizes, but also to make holes of similar description. Truthfully, their use is limited only by the users creativity!

I bit the bullet and ordered both sets directly from Hungary via the RP TOOLZ website.


They arrived quickly and were well packed in sturdy cardboard boxes.

Both sets include the die with its top plate and clamping knobs, a set of punches of varying sizes, a small hammer, and instructions in both English AND Hungarian – FELELMETES!

The round set includes a huge variety of sizes – 16 sizes, from .5mm (.020″) to 2mm (.078″)!

For this review I am focusing on the hexagonal set.

To use the punch and dies, you simply loosen the top plate…

insert a piece of material and tighten the thumbscrews…

place the punch into the corresponding hole in the die…

and give it a few firm but gentle taps!

After a few operations I had a pretty smooth flow going. For the first few cycles the punches seemed a little “sticky” in their action (RP TOOLZ gives you a heads-up about this in the instructions), but they soon smoothed out and I had a little hex-disc factory humming.

Just to see what they looked like after assembly, I glued them to the piece of styrene that I punched them from and hit them with a coat of gray Vallejo primer.

I didn’t try them with anything other than styrene, but I expect that they could be used with foil and decals too. I probably wouldn’t use them on anything harder, due to a risk of damaging the die plate, but I have not contacted the manufacturer to ask about this.

I’m very pleased with the quality of the design and execution of these tools. The rounded corners on the punch handles, recessed pockets for the size labels, the potting of the punch shaft into the punch body… all speak to the attention to detail that went into the design of these sets. They are easy to use and seem quite sturdy. I can’t wait to put them to regular use at the workbench. With God as my witness, I shall never hunger for discs and hexes of any given tiny diameter again!

You can order RP TOOLZ punch and die sets directly from the RP TOOLZ website:


I received no compensation for this review. RP TOOLZ products were acquired solely at my expense.