1

Supercharged laser cutter. Battery packs jury rigged on. Reduces charge time to none but permanently burns up a battery each use.

2

What makes a man-sized hole in a man?  Nothing like a 20mm cannon with hollow-point loads.

3

Magnetic couplers duct taped together, with an electron driver out of the deflector on the spare shuttle, to make a reactionless cultery rail gun.

4

Rigging Gun with Mining Charges strapped to the 'poons.

5

Overloading the jump drive and feeding the load back into the drive causing it to go critical and tear a hole in space as it explodes.

6

Oxygen canisters launched by jury-rigged micro thrusters.

7

Pressurized cryo-fluid canister attached to a hose and valve. The hose flails around wildly unless held down.

8

Next time we're near as we dare to a black hole, hook up the alien artifact we found (powered by higher dimensions) to our tachyon oscillator and use the resulting Hawking radiation as a makeshift wave motion gun.

9

An alien crystal shard that absorves blood, an eletric toothbrush and a hand vacuum cleanner, all taped together. I call it the V.S.T (Vampire Sucker Tooth)

10

Microfission batteries ripped from the engineering department, powering deep space search lights canaballized from the front of the ship (think backpack powered, hip fired light gun, that is so bright it blinds and gives UV burns)