The air filter I looked at for a while and made the decision that it wasn't worth making.
I got my hands on a 2nd hand air box out of a Toyota L/Cruiser 80 ser.
I cut and modified the outlet ,filled holes , cut off brackets ,made new brackets , repainted and it only took about 12 hrs.
Its a good size filter and to be honest I don't mind the way it looks , it has an old school look about it.