Marc Peltier has been working on a super-lightweight delta mechanic, based on an aluminum/polypropylene 'living hinge' sandwich material (his videos explain it better), and a lightweight water cooled hotend.
The speeds he's achieved for vase-style prints are simply amazing.
The mechanical-only kit is called 'Zatsit' and he's (after 3 years) launched a Kickstarter promoting it:
https://www.kickstarter.com/projects/39 ... inter-with
This mechanical design brings a lot of innovative thought to the problems of 3D printer mechanics, and could be leveraged for polar and SCARA mechanics also.
If you watch his videos on the kickstarter, pay attention to how almost everything uses the Hylite material - even the motor mounts. Marc has a very 'origami' way of thinking about mechanical design.
Full disclosure: I'm an early funder, and have been following Marc's work for years, and wish him the best of luck!