These trap dogs are made from 30d nails, 20d works fine too. I start out by trimming the ends off one.
then you can cold forge the end until its flat and square.
When thats done bend the flat end til it forms a "U"
Trim it off and presto! A heavy duty dog that wont bend. Just flatten then end for a regular pan or add a night latch for a PIT type pan like on this sleepy creek in the bottom pic. The whole thing takes about 2-3 minutes, costs just a few cents.