I have been trying to boolean union my polysurfaces for hours now, and I can’t seem to get it to work.
I have tried rebuilding the bad objects, rebuilding the open polysurfaces, exploding and then rejoining, flipping the polysurfaces that remain when the other disappears, as well as trying to fill in gaps with other polysurfaces. Boolean2objects worked to where I am at right now but it won’t let me do the four objects together.
Solid unions can be problematic when there is no intersection. Some of your objects are just touching so that’s one reason it fails.
If I were you I’d turn everything into meshes, join the meshes and run AlignVertices with I don’t know maybe 0.01. Then try to print this chances are the print software fixes the remaining problems.
If this fails, scale your individual parts slightly so they overlap. Then try to boolean union part after part.