I used the union tool to create this doorway, but it won’t let me walk through it.
robloxapp-20240218-1206191.wmv (1.0 MB)
Set CollisionFidelity of the Union to PreciseConvexDecomposition
When I do that, the bottom half still collides.
There’s nothing you can do about that. But there is a plugin you can use to see the decomposition geometry.
Install Mesh Optimization Tools and press Show Decomposition Geometry.
Instead of using a negative part to cut off a portion of the wall, just rebuild the wall so you make a hole in it already, then union that wall. Worked for me