You can adapt a regular handlebar grip like this...
1: Here’s the problem – most handlebar grips have a closed end. If you have a vintage bike with inverted levers – or a more recent bike with handlebar weights – you need to make a neat cut.
2: A knife makes a mess of the job, but a wooden or nylon bar makes it easy to use a wad punch – the bar gives the necessary support of an ‘anvil’ against which the punch can do its work.
3: Lucky me, I have an arbor press which makes it simple, but a hammer would also do the job. It may be necessary to turn the punch after the first blow to ensure a clean cut all the away round.
4: There we go – a nice, neat job that doesn’t look like it has been chewed out by mice. One other tip: hairspray makes a good lubricant for handlebar grips and sticks ’em in place when it dries.