Assuming the body is some sort of slippery "engineering plastic" like Delrin, I would suggest Walthers Goo.
As thick and klunky as it is, if you can get a teeny tiny blob of it on the tip of each railing wires before putting them into he
body holes, it will stick right away, and within a day or so, become semi-hard to form a really good bond that
is still flexible enough to stand up to clumsy hands. Almost anything else like ACC or epoxy will never stick
to Delrin worth a darn.
Goo is amazing stuff for sticking small parts on engine bodies into mounting holes. It's thickness is awkward. You have
to make sure you have a fresh tube. Get any of the older thick stuff out of the nozzle and get some of the more
liquidy Goo to come out before using it. It's permanent flexibility keeps
the parts in and prevents them from snapping off or otherwise getting lost where ACC and even epoxies fail.