Alan;
He is not using the rim or spokes, per his posting.
Although Michael
(OP) was not using conventional spokes, I assumed Bernie's 700c wheel was.
Whilst rebuilding my Magic Pie with the
modified spoke flange I managed to drop a nipple inside the rim, I therefore realise how easy this could happen on a construction line where you have a large box of nipples and wouldn't notice a single lost nipple.
Fortunately I noticed, because I only started with 36 nipples and ended up one short. I shook the wheel and heard the the missing nipple rattling and rolling about inside the hollow portion of the rim, until it eventually decided to surrender itself and finally dropped out.
If this nipple had remained unnoticed inside the rim, and the tyre and tube then fitted, it would be stuck rattling and rolling about for the rest of its life, as there would be no way of escape due to all the exit routes being blocked.
Alan