Opening a locked Snap-on toolbox is a do-it-yourself job. However, you should be prepared to destroy the lock. You can order a replacement lock and replacement keys from Snap-On, but you must be able to read the serial numbers on the inside of the tool box to do so. You should order a replacement lock and key of a different model number in case someone should find your old keys and decide to use them.
Check with your friends for Snap-On keys. Snap-On only makes a few different locks for its tool boxes. It is very common that a friend's keys will unlock boxes that don't belong to them. Before you drill out the lock, always ask if anyone has a spare key you can use.
Find a drill bit that will fit into the Snap-On tool box lock. The drill bit should be 2 inches long to completely drill through the lock pins in the tumbler style lock.
Align the drill bit with the top of the keyhole. Begin drilling with smooth steady pressure. When you feel the uppermost lock pin break, move down to the next. Continue drilling until each pin has been broken. Snap-on locks are tumbler locks, and they typically don't have more than five lock pins.
Insert a flathead screwdriver into the drilled-out keyhole. Turn the screwdriver as if it were the key attempting to open the lock. If the lock will not open, choose a larger drill bit and repeat steps 1 and 2.