Next up were the two internal mounting plates for triple 140mm case fans.
Another aluminum part requires another router template/jig. A 140mm fan was sacrificed for use as a router template:
3/4-inch aluminum flat bar was epoxied to the fan frame to keep it nice and square.
The fan housing was used as a guide to route out yet another full size jig. The jig was placed over a double layer of .10-inch aluminum sheet and routed out with a 1/2-inch flush/pattern router bit.
The finished cuts require zero cleanup (filing/sanding).