First up, the inner baffle that the driver bolts on to. Baltic Birch ply, 19mm. Same hole pattern as the front baffle plus an extra hole pattern matching the driver. A 45 degree chamfer x 10mm between hole positions.
The 45 degree chamfer at the back creates a free path of breathing for the back of the driver, this driver baffle gets bolted to the threaded rods of the front baffle with M8 rings + locking nuts. The driver itself bolts to the front of this panel with 8x M5 bolts + rings and locking nuts.
I’ve put 1mm thickness neoprene strips between this baffle and the front baffle before assembling and tightening the locking nuts.
The back baffle is similar in construction and dimensions as the front baffle. No driver cut-out obviously but it does have the same double construction. One 19mm outer panel and a 15mm inner panel that slides into the enclosure.
The inner back panel with a cut-out + chamfer on the inside, basically to increase internal volume.
Outer back panel of the subwoofer enclosure. Next just bolt and glue the two back panels together just like the front baffle.