This stock will glue onto the back of a Recon Nerf blaster. My son designed it and I executed it. It has a cavity (and cover) to fit the battery pack for EL wire from Electric Optics. You can print it as either a complete stock, or left/right halves. You can get a better glue joint on a left/right assembly.
It doesn't fit perfectly; you will have to shape thing a little after gluing, and you will almost certainly want to use some filler to smooth out the grip area. If you cut the spring chamber as shown in the photo, you can set it up where the blaster can still be opened after gluing on the stock. You first glue one side to the blaster and let that set, then glue the other side in place after modifying the spring chamber (so it only attaches to the bottom half). I finally got the whole thing painted; thus the new picture.
This fits the standard Nerf stock attachment, so you can easily edit the area that interfaces with the grip to customize it for another blaster.