Summary

The Hand Held Legend tactile button conversion kit https://handheldlegend.com/products/gameboy-advance-tactile-conversion-pcb-hhl relies on using the Game Boy Advance's existing membranes to give the buttons enough height to reach the new switches. However, this results in a mushy travel before the click. These 3d printed inserts slot into the bottom of your existing GBA buttons to give them enough height to click the switches directly.

Print in place. The d-pad will need supports, but the buttons can get by without supports, or with a brim.

I'd like to design posts for replacing the start & select buttons next.