Fingers crossed it'll cut ally

[Jonathan]

blu-tack might be an option for slighly larger holes, i think anything over 4 or 5mm would need a more sturdy plug

Rubber test tube bung?

I got the syringes yesterday - thank you Bigger than I expected - I'm impressed at the pressure (or lack of pressure!) that they can hold. I'll do some experimenting over the next few days...