There are so many 3D design apps. These programs can swap files if you use a common file type like .obj, glTF and .glb.

Convert glTF to GLB

NB you can convert .glTF to .glb here:

• https://glb-packer.glitch.me/

Convert OBJ to GLB

You can convert .OBJ & .MTL to a .GLB here:

• http://52.4.31.236/convertmodel.html

It is easy to get hung-up on resolution and "eye candy" and spend a long time rendering. It is important to create a range of different creative ideas and iterate concept that render fast rather than get stuck focusing on having "all the bells and whistles" or high-resolution VFX that would have slow FPS (frames per second).

You can pick any of these below, however, IMHO we are concerned about User Experience (UX) for mobile users (70% of internet users) so lets Keep It Super Simple (K.I.S.S.) and be inspired by low resolution Retro Pixel Art 8-bit graphics with MagicaVoxel. These can be put into your VR app or 3D printed.

The list below of 3D apps gets progressively more complicated. There are lots of tutorial videos available.

3D Software

1. MagicaVoxel

2. MS Paint 3D

3. Tinkercad

4. SketchUp

5. Clara.io

6. Blender

7. Unity 3D

Remember you can combine your MagicaVoxel into A-Frame: https://aframe.io/docs/0.8.0/guides/building-with-magicavoxel.html