UPDATE 12 July 2020: Uploaded updated parts. Base is now a bit slimmer, has a nice curve at the front and is reinforced at the back. Arm is more compact. Rocker is updated to match new arm position.

This is a sequential sideshifter addon for Thrustmaster T150 wheel which uses L3 and R3 buttons on the wheel's base. It's purely a mechanical solution - no soldering (at all) or modifications (almost) needed. Some additional hardware is needed to assemble it though:

Countersunk self tapping screws: 1x M4x16 1x M3x25 1x M3x16

Bolts: 2x M3x30

Screws: 1x M10x120 outer hex head 1x M3x10

Washers and nuts: 4x M3 washers 1x M10 nut