A fun online physics game

[The Farmer]

I remember playing this game a while back, but forgot about it. I didn't beat all the levels, but I got most.I kept all of my better contraptions in a text file, so I'll post them all:

~Level 3~

http://FantasticContraption.com/?designId=2169294 (mobile bridge)
http://FantasticContraption.com/?designId=2299700 (the fling)

~Level 4~
http://FantasticContraption.com/?designId=2300463 (bulldozer)

~Level 5~
http://FantasticContraption.com/?designId=2169909 (wall buster)
http://FantasticContraption.com/?designId=2202566 (Super-vaulter)
http://FantasticContraption.com/?designId=2300888 (rammer)
http://FantasticContraption.com/?designId=2342440 (needle tank)

~Level 8~
http://FantasticContraption.com/?designId=2203143 (Slingshot 0.5)

~Level 10~
http://FantasticContraption.com/?designId=2216454 (tank)

~Level 12~
http://FantasticContraption.com/?designId=2172999 (tail and boat (p.s. I have no idea why I named it that))
http://FantasticContraption.com/?designId=2216819 (tank tread cage)
http://FantasticContraption.com/?designId=2343271 (long arm)

~Level 13~
http://FantasticContraption.com/?designId=2173655 (sweeping belt)

~Level 14~
http://FantasticContraption.com/?designId=2251745 (the flipper)

~Level 21~
http://FantasticContraption.com/?designId=2304854 (The crawler)