I have a pair of 3d printed heavy iron guns for Studio Series Ironhide I bought from capcomkai. They're very detailed and bigger than the dna kit. The only problem is that they attack on his back via the smokestacks. And they hang very loose and if I turn him over or shake him they'll fall loose and fall off. I tried to thicken the inside of the ports on the guns with simply paper but even then the friction was too much and it rubbed off the factory silver paint. The gun ports are an oval shape instead of a normal round shape because they have to accommodate the curvature of the smokestacks.

I reapplied enamel silver paint over the smokestacks and waited just 24 hours to try putting them on but still they rubbed off. I probably didnt wait long enough. I stripped the paint off the silver smokestacks until I can figure out what to do and repaint them again.

So now I have this dilemma that the gun ports can't be too tight to fit on the smokestacks or the paint will rub off, but if they're not tight enough then they'll be too loose for my liking and easily fall off.

Here's pics

I can't find a material to put inside the gun ports that's a compromise between being soft enough to not scratch the paint but also enough to hold friction and keep the guns on his back.

I was thinking maybe rubber, or cotton or fabric idk