Here's an economical way to make your traps. Credit goes to GIK for this neat suggestion.
Though you can give yourself a bit easier of a time if you imagine
using a full sheet for the front, then like a 20", 16", 12", 8", and finally
a 4" piece for the part in the corner. Only actually requires cutting three
pieces, because if you cut 20" of a 24" piece, you're left with the 4" piece
you need as well, and same with the 16" and 8", then you just cut one
straight down the middle for a 12" piece and you can use the other 12" piece
on the one to the side. So including the front sheet, you're using 3.5
sheets per 4' section.