fitting oversized nose

I have a 4 inch nose I want to use on a 3 inch tube. Well, it is not nearly as bad as it sounds. The tube is a little over 3 inches, and the nose is getting glued on to the payload bay so I can use the inside diameter. The gap is well under a half inch on either side when I hold it in place. Regardless, how should I fill that gap? I can think of several possible solutions but I do not like any of them that much.

Small blocks/shims of wood?

Nate

A transition/shroud, https://www.payloadbay.com/index.php?page=Tools&action=TRANS

Why do you want to do this?

Custom centering rings.

Two-part foam.

THAT'S a pretty darn handy tool! I'll be using that one!