Overview  Ski bases are thin sheets of plastic made from extruded or sintered UHMWPE (ultra-high molecular weight polyethylene).  These plastics are specially designed to absorb wax and also bond very well with epoxy.

To prepare the base material for layup simply cut the material to the desired ski shape. This is done most accurately by using a template along with a cutting tool to trace the template.   Cutting tools can range from a simple sharp utility knife to a router.    
 

Step 1: Prepare Cutting Surface  Before you begin any actual cutting of the base material, we highly recommend preparing a cutting surface especially if you plan on using a router.  This can be any smooth piece of material that you won't might cutting into.  In the picture below, some scrap piece of particle board from an old shelving unit serves as our cutting surface.

Step 2:  Clamp Template Onto Base Material  Clamp your ski template tightly onto the base material.  It's very important that neither the template or base material move while you do your cutting.  Double-sided tape along with several clamps should be enough to keep the template in place.  You'll notice that the clamps will get in the way while you're tracing the template.   Simply reposition the clamps when you get near them to get a continuous cut.  

Step 3:  Cut the Base Material   Cut the base material by slowly tracing the template with your cutting tool.   Depending on the cutter, you may have to adjust the size of the template to get the correct final dimensions of the base material.  For this example, a 1/4" diameter straight router bit fit with a 7/8" diameter ball bearing was used to trace the template above. 

To compensate for the diameter of the ball bearing and router bit the overall shape of template was reduced by approximately 0.312 inches (8mm) in order for the base material to be cut to the desired dimensions.

If you plan on using a knife to cut the base a reduction in the template's size does not need to be made.  Slowly trace or follow your template with the cutting tool of choice until you have cut out a pair of bases.  

Step 4:  Finishing the Cut  Depending on your cutting tool, depth of cut, speed of cut, and other factors you may end up with bases with edges that aren't too clean. 

Finish the bases by using a sharp razor blade to trim off the excess material followed by a rub with some fine grit sandpaper to get the sides all cleaned up.

After you're done, the base material have a nice smooth finish that is prepared for the next step of attaching the metal edges.