As Nerfer, i love the way accesories look on my blaster, but hate the fact that them fit wobbly and flimsy, so here´s a simpliest solution
Step 1: MATERIALS
You only need 3 things,
binding cover or any plastic material-like in sheet presentation (i use 16 points polypropylene, sheet)
Step 2: HANDS ON
Just cut a strip of 1.7 x 3 cm, adhere the doble-sided tap, cut the excess, and paste it over the nerf accesory, this fill the gap between pieces, i use over hand grip, blaster stock mounting part and sights, with impresive results.
If the piece still feels wobbly, just add layers until it gets the way you want