Squares are flat. Do you mean the compound of 5 cubes? https://www.software3d.com/5Cube.php I think you are asking about the extra white parts I used to add strength inside, and help to get the last part in, as seen in image below, with description "For added strength, and keeping in mind how I will...

Well done Ulrich, if you found a work-around. Here's a screenshot showing the steps, after right-clicking on desktop and selecting "NVIDIA Control Panel".

Very first thing to do would just be the Platonic solids and Archimedean solids. After that, try the Kepler-Poinsot polyhedra (small stellated dodecahedron, great stellated dodecahedron, great dodecahedron and great icosahedron, probably in that order). Then you could move onto some of the uniform p...

Correct, I wouldn't expect that to work.

Stella would print all the parts out, including the red triangles, but it can't tell you what order to put things together. You can use "Nets->Show Edge Data->Edge Connection IDs" to print IDs on tabs that you can match up though. Or just look for the triangles with matching edge lengths to connect ...

I believe I've fixed this, but not in a released version yet (and that will be a while). It only happened on some machines, especially laptops with certain graphics cards. In the meantime, you could try looking in your GPU settings for a way to adjust the level of hardware acceleration. Turning it d...

Symmetry groups in 4D are way more complicated than in 3D. I'm afraid I don't have any plans to add them at the moment. I've thought about it, and maybe some day, but won't be any time soon. Selecting subsymmetries would also be less useful at the moment in 4D than it is in 3D, as you can't create f...

Stella uses OpenGL, so any card that supports OpenGL will provide hardware acceleration. nVidia cards are generally very good for that. So yes, your GPU should make Stella render faster.

Because it doesn't happen automatically. There are different representations internally when drawing different things, and they don't all support things like this. The preview is not as important as the final.

Did you click on it for the larger image? May still not be clear, but there's a small red triangle on each side connecting the orange parts together.

My first suggestion is start simple. If you haven't made many simpler polyhedra first, I'd start there. This one's a huge project to start with. Once you've done other simpler ones, you'll probably have a better idea how to make this one. But otherwise, I would need more details to know how to help ...

It fails for the reason given in the error, no edge-tangency sphere. For rectification to work, edges are required to all be the same distance from the centre of the model. The points where edges are tangent to a sphere with that radius will be used as new vertices. With this condition, new faces ar...

The why is easy. It's because it's different code to deal with 3D and 4D.

Internally, polyhedra and polychora are scaled to a normalised size. Then scale is applied separately. In 4D I guess it's not accounting for that.

I'll look into it sometime.

I'm afraid it's not possible at the moment. I actually wanted to be able to do that, but it turned out to be quite difficult, since it knows about stellations in a symmetric way, and recognising what made up a single cell, breaking that symmetry, turned out to be a challenge. Would still like to be ...

I think this was fixed in version 5. Windows changed permissions for saving information in some places, and it meant Stella could no longer save details. Version 5 saves it differently. First thing to try would be running Stella with admin priviledges. Might allow it to save data where it's trying t...