To cut the compound angles on the cedar 4 by 12’s I made this jig which is more of a rolling trolly.
I used bed frame steel angle, and inline skate wheels. Got from Goodwill store at low cost.
I cut 10 off, 7 degree wedges off the end of a one foot wide ply off-cut using my sliding miter saw. Using screws to secure the wedges while I played around with the general arrangement, at first I thought I would need two trolleys but then I realized that I could use one trolley if I centered the axles exactly on the center of the thickness of the base. Using bed frame angle iron and 10-32 screws and nuts this was an easy task.
Setting up the saw to the workbench is a critical part of this jig, the relative height of the saw table and the squareness of the blade in two axis to the bench top required for me to carefully place wedges under each leg of the bandsaw to achieve this important setting. Also having many parallel lines in the bench top helped me a lot in the alignment of the trolley.
Finishing the square side of the cut with a small circular saw and a few strokes to complete the angle gets the waste pieces out.
I coated all sides with one coat of oil base primer then a coat of exterior latex. Liquid nails adhesive and pocket screws were used in the assembly and then a final top coat of latex was applied before filling the bed with dirt.
Video here http://youtu.be/c6JVECMb3ic
-- Love thy neighbour as thyself