Yup, anything that requires threads gets a heat set or at least a nut on the other side.
I recommend this company for the inserts (you can buy direct):
https://www.spirol.com/product/threaded-inserts-for-plastics/heat-ultrasonic-inserts/
As the MFG, Spirol also has a substantial library of...
Bit of an interesting update here!
Despite knowing the legal ramifications of using the logo are essentially zero, I really wanted this to be properly official. So, I reached out to Cave about authorization to use their logo. Because it falls well beyond the scope of typical licensing...
Title! I need a non-working Bubble System. I'm really only in need of the bottom board, hence not being too concerned with it working. I have a hunch just the bottom board will be difficult to find, though.