Hi eric, also another tip - don't try to have additional pieces like this little top hole here in the pieces you are all trying to union together:




That adds additional complexity to the booleans to try and detect a whole bunch of coincident but rotated pieces like the inside of that hole.

Try to keep things as simple as possible for a mass boolean like that and only add additional cuts like the top hole at the very end after the larger piece is all together.

- Michael