Splitboard/Junkboard in Make: magazine
Snowboard conversion to DIY splitboard
I think it's funny that it has gone commercial in that a manufacturer is selling a kit for it. It also looks like the intent is only for skinning up, and not sliding down.
Splitboards and junkboard skis use similar materials for different purposes. Splits allow snowboarders to more easily access backcountry terrain and traverse/climb slopes but still descend like a regular snowboard. Junk boards are simply short wide skis made from a junk snowboard that you can trash and not worry about it when the conditions are highly marginal.
You can buy splitboards from the factory with the kits already installed from lots of manufacturers. Some easily in the $1000 range. The Voile split kit has been available for a long time and lets you use a board you already own.
Junk boards come from ski swaps and trash cans, IMO. They aren't your primary go to gear, they seem like a way to extend your season.