Ping pong gun + Christmas cracker

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I invented a spring-lever unit (superspring). And here are various things based on it: 
- Ping-pong gun; 
- Christmas cracker;
- Spring-lever units.

Are parallel springs better than series springs? They store the same energy, but... Parallel spring doesn't change volume when loaded (ideal for accumulators). And it accelerates a light lever to tremendous speed (like a bow/crossbow). 

Just imagine a spring accumulator the size of a book. You insert this charged accumulator into a bicycle and can ride for 10 minutes. I'll try to make this soon :)

Print-in-place, no support,
0.4 mm nozzle, 0.2 mm layer height, 60 mm printing speed.
Any non-fragile PLA

Warning! This ping-pong gun has a very tense lower link. It can gradually stretch and break. Mine lasts about 50 shots before it breaks (the plastic is ESUN PLA+). I might soon redesign this gun, either removing this thin link or making it quick-changeable.