This is a regular amp that I took apart and replaced with 3d printed part so it would match my Prusacaster. 

The inserts are used in the top and bottom pieces, 4 holes each. 4 holes on the sides to hold the back on. 4 holes on sides of grill and 4 holes in speaker plate.  I used M3 x 18mm screws to put everything together.  4 M3 nyloc nuts needed to hold speaker in place. 

Link to Amazon AMP: https://amzn.to/3NtxVz2 (aff)

Link to heat inserts I use: https://amzn.to/3raMCzy (aff)

Link to screws: https://amzn.to/44i15rs (aff)

Link to Nyloc nuts: https://amzn.to/3r6incW (aff)