Welcome nutz4tools
I use machinists jacks continually, setups, inspection, and repairs. A lot of companies make jacks; Armstrong, Starrett, General, to name a few display the range in size, features and price. Armstrong's are incredibly sturdy. Starrett has a variety of adapters. General is reasonably priced. Each has a good feature to exploit; and each share certain disadvantages.

1) All have a proportionally lowest height restricted by the common centerline of screw and body. This will answer a need different than common machinist jacks.
2) If you target the machinist and engineer crowd; one or two jacks often is sufficient but a set is [I]Three[I]! One is at convenient height, other two manipulated for adjustment, leveling in particular. Leveling, inclines, or compound angles easiest when all planes X-Y-Z can be compensated with same thread pitch in each jack.
3) Same crowd will tell you, too many use proprietary threads. Occasionally, a substitute threaded portion is needed that odd threads will not accommodate. Also fine pitch threads adjust better, with higher strength.

I'd like to see you successful peddling quality innovative jacks. I don't want a cent of compensation, other than a tip of the hat.