This post shows how to make that jig.
The jig requires two pieces of plywood approximately 10” x 16” to use as runners along your fence, a piece of plywood 10″ long x the width of your fence (plus a hair) to straddle your fence and two piece of wood at 1 ¾” x 1 ¾” x 10” to form the cradle that holds your workpiece, plus stock for a handle (optional). None of the sizes are essential except for your fence width, so these are ballpark figures. woodworking tips and tricks for beginners woodworking tips video
CREATING THE SPLINE JIG
To make the jig, I began by cutting the larger two pieces of plywood to size and rounding over the edges. Then I ripped a piece of plywood that is exactly the width of my fence plus a hair and cut it to 10” long. This is the most important measurement of the jig. woodworking tips and tricks for beginners woodworking tips video
You are going to attach the two pieces of wood (runners) with this one in between so that you can slide the whole jig along the fence. If you cut the piece too wide, the jig will wiggle from side to side and you will end up with sloppy splines. If it is too narrow, your jig won’t slide at all. woodworking tips and tricks for beginners woodworking tips video