I must rebuild the handle on my wife's ultralite spinning rod. She must have a 10-11 inch handle behind the reel seat because of some physical limitations. She wants a foam handle instead of cork if possible.
The rod measures 9/32-inch OD approx. 1 1/4-inch in front of the cucrrent handle. I am assuming I need 1/4-inch ID material for the handle.
I have been unable to locate any EVA or Hapalon straight handle material with 1/4-inch ID hole.

Can anyone suggest a source for foam handle material for this application OR should I attempt to use 3/8-inch ID material? (I think I saw some of that on one web site)

It is really not a big deal.
Find a foam handle that is as close as you can get to what you need.
If you have a lathe, you can use the lathe to shape it to the shape that you want.
Then, if the center hole is too large in the foam, simply use an arbor - foam, tape, or dry wall tape to build up the blank to make a snug fit for the foam handle. Then, epoxy the handle in place and you will be good to go.

Sure, if you are normally building big rods, it is nice to have a stretch fit of a foam handle to a blank, but the use of an arbor to build out the blank works just fine.

Take care
Roger

I'm sure one of our board sponsors would have 1/4" EVA. Unfortunately that length in 1/4" is not common. Like Roger said, not a huge deal if it's a little too big, but the stretch fit is what secures the EVA to the blank with a thin layer of adhesive (strongest). Call around, or check the websites. Failing that, try and keep the gap between blank and EVA to a minimum,and shim with thread or small tape wraps.