Here's the template on the planking. I've shifted it over by five mil so as not to end the cut at the very corner of the timber and then marked the footprint of the pair of skis before adding the same type of chamfer to the opposite side. All being well we shall be able to put the wedge-shaped off-cuts to good use when it comes to fixing the forward end of the skis.
We could use the one remains square of backer-board for all of this but timber has to be quicker and sturdier. These hubs where lats and skis meet however are ideally suited to 3-D printing in the longer term.
