240 Headunit fascia template
If you're mounting a standard 1-DIN head unit in the lower spot in a 240, I've made up a handy template you can use. All you need is some aluminium sheet, you want it to be fairly rigid as the head unit will hang off of this, 3mm is a good choice.
All you need to do is print this out exactly 1:1 using the included measurement to test your scaling, then glue the printout onto a piece of aluminium sheet and cut and drill. You do need to round the corners off but you won't see them when installed so if you just rough them in with the dremel or a file or something, no harm done.