I thought to use one of spare inner tubes but I am not sure if it can be bent painless.The alternative would be to get some of the automotive tubing sold which is softer and easier to reform but you would need the correct O.D. to fit the I.D. of the hole in the stem, cutting the angle is easy
I would appreciate a direction where to buy them.You can still buy the innertube inserts for around $6.95 for a pack of 3 I believe but they only come in one length and it is straight.
You can bend a pipe by inserting a pull spring inside it before bending. The spring has to fit correctly, though. this prevents it kinking and helps get a consistent curve. I'm sure one of the correct size can be found for the job.Don't know if one of the current straight ones would be long enough, or if you could bend one without kinking it
Actually I didn't start yet I do completely agree, the construction looks difficult to assemble. It can exist only if at least one part of tube (inside of the stem or inside of the stummel) is ideally straight and is not fixed, i.e. it can be turned round easily inside that part of the pipe.Do not bend an inner tube, the way the patent drawing shows, it would be impossible to remove the stem. I think the patent artist erred. If you want to try an inner tube in a bent pipe, it must be short enough that it terminates in the tenon funnel.
Thank you!Sometimes the right size spring can be kinda hard to find, you can pick up a line forming tool for about $18 or less. Check Northern tools or maybe Harbor Freight