Here are pictures of the prototype 9 meter telescoping mast for the 251, there appears to be several version of telescoping masts used on various vehicles, this one was designed from a lined drawing as the only photos I could find did not give enough detail. The mast is mostly shown in the retracted position, I only have one picture, not very clear of it extended when it was on display at OSF. when fully extended if is over 6 feet tall. Still some work to do on it, more detail needs to be added to the crank box and main base upright tube.
This is basically a 100% hand made from telescoping brass tubing which is .028" thick. All hand cut and soldered. The mast, scaled one that is, is held erect by a single length of copper wire that is treaded through holes in each tube starting at the bottom and working to the top. Takes about 5 minutes to do it. How it is done is a secret at the moment. took me a few hours to figure it out.
As these will be all hand made, they will be expensive, there is no way to mass produce it that I can think of in small numbers. If you have an interest let me know.
Here are the pictures