What follows hopes to be a simple, cheap and effective way of converting any Paintball marker to fire BB's at high velocity. Beware that this is in no way safe to use on the field unless well tested and adjusted on a chronograph to avoid injury.
Disclaimer: I will not be held responsible for your actions and any injuries that result from the making or usage of this device.
Step 1: What you'll need
Basically you need to start by gathering the following tools and resources
Step 2: Start making
Drill a 7mm hole into the side of the barrel about 3 to 4 cm/1 to 1.5 inches from the thread (Make sure that the hole will be on the top or slightly to the side of top when the barrel is screwed in), this is where the BB feed will eventually enter your barrel. U should know that this device uses a BB barrel inside a PB barrel.(Please read the entire Instructable thoroughly before drilling)
Step 3: Making the bullet control point
Drill 4 holes into the wooden dowel to create something like the pics.
The dowel is cut to about 3cm/1 inch long.
Step 4: Putting it all together
Slide the BB barrel into the corresponding hole in the control unit and epoxy it in place.
Slide the Control Unit into the PB barrel until the two feed-holes Line up and epoxy into place (the epoxy is to prevent the "Unit" from becoming a bullet while shooting.
Stuff the space between the Barrels with tissue or newspaper (or preferably Epoxy or Bondo, but I didn't have that much to waste), Get the BB barrel centered as good as possible, as this is going to define the accuracy U get from the device.
Slide a short (5cm/2Inches max) portion of the barrel onto the feed holes, not to deep (there should still be enough space for the BBs to move from The feed portion into the main barrel)
Step 5: Finishing up
Drill a 7mm hole in the bottom of the Pill bottle where it will fit over the feed portion and feed BBs into the system.