Invisible cylinder

[polo2010]

I am using the invisible box and now try to do a similar one but as a invisible cylinder - I check the box mtl and obj, compare the invisible box's mtl and obj, now how to do an invisible cylinder?

[Puybaret]

In a mtl file, the number following d matches how transparent is a material from 0 (fully transparent) to 1 (fully opaque).
You can try on a cylinder but don't expect to make round holes in walls with such an object.
If this was your final goal, see this thread for a workaround.

[polo2010]

I am trying the work around. I don't want a round whole in the wall - I am using the "wall" to create a 20 cm thick 300 x 500 ceiling and place the new "round tool" 10x10 so I get a series of small round wholes. I copy as new furniture and elevate to my ceiling height. Then I give texture and place small light bulbs inside the small wholes to get an embedded light source, that you often see in ceilings and canopys in interior design magazines. I am not good at adding light sources, but it seems to come out fine.