Necessity is often the "mother of invention" so when my return to RPG required a "new monster model" for the adventurers to gawp at, and a similar one kind-of existed (squint and you could see it) .. I picked up my paint brush and had a go to "transform" creature 'A' into creature 'B' (see below, a Nothic is a transmuted magic-user who like Icarus flew too close to the sun and got burned [deformed] badly - in particular he has a big bad eye ranged attack weapon. The model was a previously run of the mill "Carrion Crawler"):
Well I had plastic a "Carrion Crawler" spooned from a boxed game which looked hideous enough - so instead of letting it see through some 'slug stalks' I pained a large green eye in the middle of the creatures forehead. It works for me .. the only bad thing was that through an ingenious use of a light spell on its eye by a brave cleric - the thing was blinded and then killed by the party - although it nearly took the party's leader (a Magic-User) out. However, it did take the adventurers most of the night to overcome this foe, so that was a RPG result!