This is a simple chassis using just 4 aluminium panels and 2 heatsinks. Designed around dimensions to tightly pack in a LM3886 chip amp kit.
The top and bottom pannels sit in ridges cut into the heatsinks with a table saw, and then the front and back panels just bolt into the end fins.
Rear panel fixings are held with M3 nut and bolts, and panels that join to the heatsinks are held by M4 bolts tapped directly into the heatsinks so no additional brackets are required.
Heatsinks are 75 x 160 x 50mm with a 10mm thick base.
Front and back panels are 8mm, and top/bottom 3mm.