https://www.amazon.com/dp/B072JQRFNN/ref=cm_sw_r_cp_api_i_QuMPDbJ8GXS9F. I used that as the base with a repaint. Then I added cable cover over the hose (painting it made it sticky). The biggest mod I did was to the “gun” so I ended up cutting most of it down and housing it in a PVC tube. Not screen accurate by any means, but it’s close enough for a dog!
Edit: the whole base sticks to the back of her vest with just Velcro. It would still function as a water gun, but I don’t feel like making her haul however much water that is on her back. She’s 11 years old and arthritis is an issue for her some days.