So, I am making a tycoon game, and the wall is shaped like a ring. I used the negate part to make a doorway through the outer ring, but for some reason, I couldn't walk through it when I union it. What is happening? Also, if anyone knows how I can show some pictures, please let me know!
THE ANSWER IS: DON'T USE UNIONS OR MAKE UNION NON COLLIDING. Unions are weird and doesn't work the perfect way you think they will work. You need to make the part that blocking you a non colliding and and weld/anchor that part then add invisible parts/bricks that will collide there where you need collision. To let us understand better let you show some vids / gifs when you play that.
https://blog.roblox.com/2014/08/solid-modeling-is-here-a-new-way-to-build/
ROBLOX currently only supports collisions between convex shapes (no holes, indentations or valleys). The current shapes we support are blocks, spheres, wedges and corner wedges.
BTW u can upload screenshots on imgur.com and just give us link.
PS. Also remember to customize CustomPsyhicalProperties and set the mass to the correct one cause if your doors are too heavy then with normal gravity settings you cannot move them as normal roblox character.
I cannot help you more. Roblox su$%# and union system isn't good for things like cylinders.