I know it is too late for this year, but has anyone got a good/effective design for shed traps
I don't think it's too late yet -- some bucks are still carrying. But, in some states shed traps are illegal. In Pennsylvania anything that unnaturally causes antlers to drop is illegal.
Here's an idea I haven't tried. Drill two small holes in the lid of a plastic peanut butter jar and screw it to a tree about 8" below a limb. Then cut the bottom out of the peanut butter jar, making sure there are no sharp edges. Put the jar on the lid. Deer will come to lick the peanut butter and if it's a buck that's about ready to drop, the limb above the peanut butter jar might give them a little assist. Put up a trail camera so you can see what's coming to the peanut butter.
Just a thought.