For the past 2 years I've built my teams arms, all of which are telescoping. We use extruded aluminum. If you have any questions or need any help just PM me. If your only doing 1 extension it's quite easy, but as you get to 2 or 3 extensions, it gets a little tricky. You can use both cable and chain. As of right now I only know how to use chain for 1 extension

, but i hope to change that soon.
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Whats the difference between mechanical engineers and civil engineers?
Mechanical engineers build weapons, civil engineers build targets