From what we can see on the various screenshots taken from the trailers, the Rebel DH17 Blasters seem to be in a carbine-type configuration in Rogue One which makes them look a little bulkier.
Since I had the Hasbro Nerf Blaster, I decided to give it an AR-type stock.
Here you go:
The "buffer tube" is made from a solid piece of round plastic and is glued to the end cap of the Blaster body.
We made a groove in the underside of the buffer tube and inserted a rail in which the length adjustment pin of the stock can lock the stock in place at the desired position.
A metal rod is centered in the buffer tube and reaches into the Blaster body through the end cap.
I drilled a hole into the underside of the end cap through which I poured a two-component liquid plastic which solidified around the rod in the end cap and a) adds weight to the Blaster and b) keeps the rod securely in place.
Does that make any sense?
BTW: yes, I left the Star Wars, license and other markings on the Blaster body in order to give any authorities something to look at in case they decide to do a weapons check while going to or back from an event.
There will be no question if this is a toy/prop or a real weapon.