A nerf H.A.M.P is a really cheep (less than $5) nerf gun that does not use any springs, weights, pulleys, or pumps. The whole gun is made out of stuff you can find at a good hardware store.
I am a beginner at making nerf homemades... so bare with me.
Hacksaw, Dremel, pipe cutter, or anything else that can cleanly cut PVC (NOT CPVC)
Hot glue gun and hot glue
(Optional) Flat, heavy weight
PVC cement (I also used a primer which I highly suggest)
Lazer level (or just use a lazer or a ruler)
DUCT tape (NOT DUCK TAPE)
Lots of E-Tape (electrical tape)
2" inch PVC about 2 feet
(1) 2'' inch PVC coupler
1.5" inch PVC about 3 feet
1/2" inch PVC about 6 feet
(1) 1/2'' inch PVC ''T"
(2) 90 degree 1/2" inch PVC elbows
As many bushings as it takes to get from 2" inch PVC to 1/2" inch PVC
Nerf darts, Screamers work the best (Streamlines kinda don't work)
Some sort of Plastic/ Tape friendly Lube
Step 1: Body and plunger
Cutting the body:
The body (2'' inch PVC) should just be just long enough so your non dominant hand can still stretch forward a good 10 inches (look at the photo)
I used a black 1.5'' inch piece of PVC
Cut on the longer side of your piece of PVC about three fingers down