How do I use a .bsg file?

Slider Engine

uploaded by The J 1 week ago

An engine that moves the cannons side to side to alternate pushing the pistons. It's one of my smoothest engines for certain, and it gets up to speed extremely quickly, so I'm really happy with it.
posted by oziboy 6 days ago
Looks pretty neat

Could have been faster but that's besieges problem not yours