Amps racks! I'm using a pair of Zapco Z150.4LX 4x150 to power the front stage (one amp left, one amp right. Ch1 TW, CH2 MR, CH3&4 Bridged to MB) and a 1k to power the sub. The sub amp is hidden behind one of the visible amp racks and attached using riv nuts and hex head bolts.
First thing I did was build a replica of the amp out of chip board and CA glue. This lets me use this during mock up and fabrication without any risk of damaging the amplifiers.
Next was the construction of the amp racks. The racks themselves are made from welded steel box tubing with wood and body filler cover panels. Rack are bolted to the body of the car using hex head machine screws and riv nuts. The cover panels are attached using neo magnets.