RE: DA-85 Question
It's actually silicon tubing. You can find that in various places.
I've also seen people using the black tubing that is normally used for smoke.
Be aware that the canister sends the vibrations into the fuselage. You will also need to put a piece of silicon exactly where the can passes under the gear. If they touch, it could create interferences and mess up with your radio. We lost three of these at my club...