Looking to print a new part for a home appliance. There's going to need to be a new model created with the customizations made, but the model (after printing) will have to fit where the old part was. Is there any 3D modeling software that is better for this purpose? Will I just have to guess at proper proportions and hand-adjust the scaling of each dimension and angle through trial and error until a version fits?

  • $\begingroup$ You can usually measure most dimensions with a digital caliper and enter them as parameters into your model. But curves, angles and such are more difficult to get right. I often print small sections or slices of my whole model to check for fit against existing parts. For example in PrusaSlicer you can cut a model into pieces with a few clicks, and then only print the part that requires “verification in print.” This way you waste minimal amounts of time and filament, and can be relatively certain that the big, final part fits on first attempt. $\endgroup$
    – Christoph
    May 11, 2022 at 2:34

2 Answers 2


Use software specifically designed for making parts with specific dimensions and then measure exactly what you need and design from the measurements.

I use Freecad for this sort of thing but there are plenty of others that let you precisely control the measurements.

Most 3d software could probably manage it, but if you use one specifically designed for this sort of work there is less of a learning curve and you don't have to mess around learning irrelevant stuff.

  • $\begingroup$ Basically any engineering cad package would work. OpenSCAD, fusion360, freecad, others that are not free.. $\endgroup$
    – user10489
    May 8, 2022 at 18:21
  • $\begingroup$ My average record for doing this sort of thing is to measure carefully it but still have to print 3 prototype parts and tweak dimensions each time to get it to fit. $\endgroup$
    – user10489
    May 8, 2022 at 18:25
  • $\begingroup$ @user10489 I have better luck I guess, it usually works first time for me. But I'm an engineer so I'm used to fabricating things. And I drill holes and things rather than print them. $\endgroup$
    – Kilisi
    May 8, 2022 at 22:11
  • $\begingroup$ You have better luck or your printer is better calibrated or you are less picky. :) Sometimes I drill holes (or make them bigger), and then fix them when I find a second dimension that isn't perfect. $\endgroup$
    – user10489
    May 9, 2022 at 1:11
  • $\begingroup$ Any pros/cons in what software to select? $\endgroup$ May 9, 2022 at 2:23

Use a CAD software

Whenever you need to make a part fit given dimensions, it is best to set those. There are tons of Computer Aided Design software packages around, starting at free and ending at thousands a year for a single PC license. There are so many, that Wikipedia made a comparison list

all3Dp always curates a list of free 3D software. Among them, I can point to the following as options:

  • I personally prefer Fusion 360 by Autodesk, which is quite powerful but slightly cut down in the free version. It is known to produce very good exportable designs but has a somewhat steep learning curve. It also allows parametric designs, very valuable if you need to customize items.
  • Onshape is similar to Fusion 360 in that Hobbyists get it free, but it is browser-based, making it possibly easier accessible. It is a full-powered CAD suite, including parametric design.
  • FreeCAD might not be as powerful or fancy as Fusion360 and Onshape, but it is a solid, well-working CAD package. It has also a somewhat easier learning curve than the likes. It allows entering OpenSCAD code, which means, you can add mathematic formulae to design your part.
  • OpenSCAD is the absolute barebone, but absolutely parametric. It takes mathematical descriptions of bodies to design them - which is hard to learn and master but allows to create some very intricate mathematical models.
  • SketchUp Free has a dubious reputation among printing enthusiasts, as its STL solutions at times have inverted surfaces.

Not on the curated list of all3dp is one entry I personally worked with and which is somewhat potent but easy to use:

  • DesignSpark Mechanical is a derivative of the powerful Ansys Space Claim CAD software and is offered for free. It is somewhat limited though.

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