Ahoihoi

Not as detailed as usual, but this time I had to figure out how, then make the thing, and then show the details

and parts. Its not a step-by-step, but the skilled selfmaker will know how to copy it :) and the skilled hobbiest

will even manage to get it done in a more simple way...and here we go:

Tools:

- Dremel Tool (drill bits and cutting wheel)

- Drillpress or stronger electric drill for the bigger holes in the wooden mag

- Soldering iron

- Pliers and wire cutter

- Screwdriver

- Working knife

Material:
- Aluminum U section, 35mm wide, for the base

- Alu U section for the cocking-sled, 40mm wide (or similar, they have to fit each other)

- Alu L section 10x10mm also for the sled

- Scrap sheet aluminum for the lock, 5-6mm thick

- 15mm wide and 0.8mm thick spring steel for the bow

- Steel string (solderable) 1mm

- Alu L section 30x30mm for the syring-mount and bow limbs mounts

- Alu square-bar 10x10mm on the syringe, gets caught in the lock

- Alu square pipe as a guide for the square-bar

- Plastic spacers 10mm or tubing (pillars for the square-pip guide)

- M3 screws and some M2 screws (smaller screws for mounting the covers

- Rectangular Alu pipes and U sections for the covers.

- 1 Plastic syringe 100-200mL

- Scrap wood (for the mag), 15mm thick plastic or metal will work as well

- Brass barrel (15-20cm long, 6mm outer diameter, 5.1mm ID)

- 5mm magnet to hold the BBs

- 5mm BBs

- Small tension spring for the lock/trigger

- Tiny o-rings

- M5 screw

Step 1: Bow Limbs and Mount

Cut off 2 L-section pieces from the 30mm Alu L, 60mm long. Cut 2 pieces with the cutting wheel, about 110mm long, and another 2, but only 70-80mm long.

2 holes, 4mm diameter each as shown, mark the holes on the 2 L sections. Attach 2 on each L. Tiny hole for the string (measure 90-100mm from bottom) only 1mm.

Mount them on your U-section base. Then solder the string in.

Step 2: Syringe Mount and Re-inforcement Plate

Fabricate a syring mount from 30mm L section. Place it as shown on the U-base. Give the bow a bit of tension, then mark the spot and srew it on. 4 holes in the pistons rear part, 4 spacers and a baseplate.

Drill a hole right in the center or the baseplate, 3-4mm. Cut 95mm of Alu square bar. cut out a catch as shown,

M3 or better M4 thread into the other side. Then mount the bar on the plate. I drilled 7mm holes to make it lighter, thats up to you. Lighter means more power though :>

Step 3: Guiding Pipe

Cut a 45mm long piece of square-pipe, drill 2 holes to mount it and attach as shown. Make sure it lines up well with the syringe-piston and follows its direction, or it will jam or sit too tight.

Step 4: Lock/trigger

Cut out the parts (templates above) and put them together as shown. Attach the plate in line with the square-bar's catch. I used 2 thin plastic spacers between lock-parts and their baseplate, to minimize friction. You also want to glue the mouting screws with some locktite or a drop of clearcoat, nailpolish or whatever you got. The 2 parts have to move freely and smoothly, but without coming off sooner or later ;)

Step 5: Mag and Cover-plate

Fabricate a mag as shown, wood or whatever you got available, Alu would be even better. Drill holes as shown, fabricate a cover-plate. M5 screw plus o-ring, M3 screw on the other side, and we are almost done.

Step 6: Instructional Video

For the covers and body, you are free to to whatever you want. A simple grip will do, if you want to go fancy, try it out and make your own design :)
The video will hopefully help you to get it done, its really not a starter-project, but fun!