discussion Best approaches for designing and printing custom parts for scale models?

[reynsi]

Hi everyone,

I’m getting into 3D printing specifically to help with my scale modelling projects and would love some community insight.

I’ve seen members discuss printing missing or customised parts for kits and scratch builds, but I’m unsure about the best workflow from design to final model.

What CAD software do you recommend for designing parts that will fit accurately into existing kits? How do you handle scaling details without losing fidelity?

Any tips for successful prints (resin vs FDM) and post‑print finishing techniques that work well for scale models would be really appreciated!

 

[reynsi]

Hi everyone,

I’m getting into 3D printing specifically to help with my scale modelling projects and would love some community insight.

I’ve seen members discuss printing missing or customised parts for kits and scratch builds, but I’m unsure about the best workflow from design to final model.

What CAD software do you recommend for designing parts that will fit accurately into existing kits? How do you handle scaling details without losing fidelity?

Any tips for successful prints (resin vs FDM), using a 3D Printing Service, and post‑print finishing techniques that work well for scale models would be really appreciated!

thanks in advance for any help

 

[Steven000]

...What CAD software do you recommend for designing parts that will fit accurately into existing kits? How do you handle scaling details without losing fidelity?

Any tips for successful prints (resin vs FDM) and post‑print finishing techniques that work well for scale models would be really appreciated!

I use some old software from work, but if I have to recommend software I would say try to learn 'Autodesk Fusion (Fusion 360)' which is free for personal use and is quite popular.

I measure existing parts with calipers.
If you need to remodel something with a complex outline/cross section you can 2d scan the part or take a photo, then use the image on a 2d-plane in the software, scale it to your measurements and draw your new part on top of the image so it will fit the outline.

I designed a lot of models in the past for any scale and most of the times details are adapted to the scale; a U shaped handle on a tiger tank in 1/35 would be designed like the real thing - but in 1/144 it might be too fragile in resin to clean, or causing misprints, so that same handle could be drawn as a tiny box with rouned corners.

The same goes for tickness, a part in 1/35 with thin walls will get too thin if you just scale it down to 1/144 and send it to the printer. So you need to design the part for the scale you want it to be.

I use both FDM and resin, I don't recommend FDM for typical fine scale models but it works for very large scales. FDM is great for tools or even diorama bases that get either sanded or textured with earth/mud/stones.

Hope this helps somewhat, goodluck, cheers

 

[A7man]

Hi reynsi,
I have used several different cad programmes and at the moment I just use DesignSpark mechanical and SolidEdge. DS is free for the basic version, which does everything I need. There are some limitations, but trying it won't cost anything. SE has a community edition which is also free, again some limitations but an incredibly well featured programme. Both programmes will export stl for 3D printing. SE is a bit fussy about the export settings. I tried Fusion some years ago, but then they changed the rules on what you could do with it, so I dropped it. As far as I know, FreeCAD is the only free cad package that will always be free. FC has a reputation for being a bit awkward to use. It is, but I have created some good designs, 3D printed them, and then cast them in aluminium. I don't use it anymore because the first two programmes mentioned here are easier to use. However, if both DS and SE stopped doing a free version of their cad programmes, I would pick up FreeCAD again. I download major versions of FC to try out and keep up to date.
Lee

 

[Witabir]

Hi everyone,

I’m getting into 3D printing specifically to help with my scale modelling projects and would love some community insight.

I’ve seen members discuss printing missing or customised parts for kits and scratch builds, but I’m unsure about the best workflow from design to final model.

What CAD software do you recommend for designing parts that will fit accurately into existing kits? How do you handle scaling details without losing fidelity?

Any tips for successful prints (resin vs FDM) and post‑print finishing techniques that work well for scale models would be really appreciated!

Good topic — scale modelling is one of the areas where 3D printing really shines, but also where small mistakes become very obvious.

For CAD, accuracy matters more than “power.” A lot of people start with something like Fusion 360 or similar parametric tools because they let you define dimensions precisely and easily adjust them when something doesn’t fit. That’s especially useful when you’re matching existing kit parts rather than designing from scratch. The key workflow is usually: measure first, model second, and always assume you’ll need at least one test fit iteration.

On scaling details, the trick is not just shrinking or enlarging uniformly, but thinking in terms of printability. Very fine rivets, panel lines, or mechanical details often need to be slightly exaggerated in CAD so they don’t disappear after printing and cleanup. Otherwise, what looks correct on screen ends up too soft in the final part.

As for resin vs FDM, most scale modellers end up leaning toward resin for detail work. FDM is fine for larger structural parts, jigs, or rough prototypes, but layer lines and minimum feature size can be limiting at small scales. Resin gives you much better surface quality, but you trade that for more post-processing (washing, curing, careful support removal).

Post-processing is almost a discipline on its own: careful sanding, priming, and sometimes re-scribing panel lines after cleanup. Primer is especially important because it reveals imperfections you won’t see on raw prints.