I originally learned that i-adjectives are joined with くて e.g.
I want a long, red fish.
Recently I've come across a couple of examples where the two adjectives are joined together with the omission of the い from the first e.g.
Thin, long rectangle
Is this something I can do with any pair of i-adjectives or just ones of the same type (ones that describe size in this case), or are there only specific pairings that are allowed?