i say the bike and fridge look the most interesting

although the bike in the picture doesn't look abandoned so you'd have to get creative in making it look abandoned

the radio looks alright to do but it looks like there is no challenge to it. all you'd have to do is fiddle around with a few polygon primitives

the fridge looks like it would need more work than the radio since it has all those dents

whats the purpose of this summer challenge?