Ok last night i won on ebay a pencil top which i using as a valve cap 
I believe it to be the ultimate i valve technology
A sponge is porous. It won’t hold air. Not a good valve.
Lol, wait are you kidding? I dont get it. that must!
Thats wicked!! I think i might steal that idea…
you bought this on ebay?
pencils are literally the same size as a valve for any car or bike. Hense most will fit with or witout little modification
If you look for car valve caps you only find half a dozen types MAX, and believe me they crap 
Best to get a pencil top, i have seen hedgehogs, springy animals, pigs, list goes on
unicyclers for christ: