One of my four sons received this for Christmas and we have been having a blast with it! The box got thrown out before I read the directions so I simply went on the Crayola website and watched the demo. We have the locking problem that it seems like everyone is having but a screwdriver pops it right open. Obviously the lock could have been better designed but.... Overall, we are having a lot of fun with this and have made tons of really cool cars! If you use enough crayon, the body "snaps" onto the chasis and doesn't come off until you take it off. It's important to be patient and wait until the body is completely cool before trying to take it out of the mold. It's a good lesson for four little boys :-)