meagain The 'legal' part comes from them being hydraulic. Maybe that guy has mad e a deal with the patent owner. If you sold frame only, and let they buyer's supply their own jack/hydraulic system, you'd be good to go. 'There was a frame made a few years ago, but I've never seen them for sale to the public, nor seen them in any ads. The builder was a member of the Golfclub makers forum/assoc., or whatever it is/was. scotts33 would know who I'm talking about.
This is the one my brother was making. iirc, Landon is now in possession of this exact one.