I figured out the problem: I was using the wrong formula to calculate the vertices so the ones I had were creating coplanar faces so that's probably why it was crashing. Once I fixed the formula it worked no problems.

I made the following .off file but when I open it in stella4d and ask it to make convex hull the program crashes. Do you know what could be the problem?

cylindrical crind.off

Yes, convex hull is what I need and it works just fine. Thanks again

It got confused when I listed cells, but I did a listing of just the vertices and it created the 4D convex hull for me! Thanks for your help.

I'm trying to work with .off files to create 4D non-uniforms, but it's way too tedious to try to figure out all the faces and cells that would connect the vertices. I found this program called qhull (www.qhull.org) that will calculate the convex hull and create an .off file from input vertices, but ...

What about an ability to cut off pieces of uniform polyhedra? That would give rise to lots of interesting non-uniforms. Maybe create it by choosing a cross section to cut it at (this could really be a great feature for 3D also!).

I just got Stella4D and I'm trying to play around with it. It seems you covered pretty extensively 4D uniforms, but I had trouble trying to create non-uniforms. I wanted to make an Icosahedral pyramid, for example, so I tried using a J2 pentagonal pyramid as vertex figure to create it, but it only g...

That's good to know. Thanks again

Never mind, it seems that feature is already available and I overlooked it.

Could there be a way to choose which matching face of existing polyhedron is used for augmentations? Often I find I want to use a different one than which is automatically chosen.
Thanks

And an alternate version with antiprism and cupola replacing rotunda:

Even better, I got one with a genus of 6 and retaining the original symmetry of J76 by cutting through with a Dodecahedron and 5 J11s
Still quasi-convex!

So I created a new toroid that has Stewart's quasi-convex property that doesn't seem to be mentioned in his book (I only have first edition, though): This is J76 with a rotunda and two icosahedra removed for a genus of 2.

I found another interesting one yesterday:
This is a J91+J63 Tunnel through a J32 (Pentagonal Orthocupolarontunda)

I realized then that J32 had a cross section of 2 of those irregular hexagons that Stewart talked about inside a Rhombicosidodecahedron.

Maybe you by accident selected "no tabs" in the menu? Do the tabs show up on the print preview?