Wood – How to hang wood letters

Sorry. My first answer mis-understoood the question. Based on the updated question, there are many ways to create a shape of the desired profile, based on what tools you have or can find/buy/etc.

• Rip the edges with an angled tablesaw blade.
• A handheld power (circular) saw, with the blade at an angle. A fence will help you get a straight edge.
• A jointer.
• A handheld power jointer.
• A hand plane. A good craftsman with a sharp jointer plane can do this easily.
• A router table.
• A handheld router.
• A millwork shop can easily turn this profile out, so you can always buy it ready made, for a price.
• If you have a friend with any of the above power tools, I'll bet they can be bought off for the price of a pizza.

Very much depends on what tools you have, how much money you want to spend. You can use it to justify buying a specific tool, if you have a use for one of the tools I've mentioned. They are all useful.

A tablesaw or a router are both terribly useful tools, but if this is a one time job and you have no interest in woodworking, then I'd look for a friend who can help you out. If you insist on doing it yourself, and might have an occasional use for a hand held circular saw, then go that route. A circular saw will be often enough of use even to someone who is not an avid woodworker.

Attach your board to a straight piece of wood to use as a fence. Then angle the blade, and rip the edge as you want it. I'll argue this is the cheapest solution that will give you a good edge. (A hand held jointer plane might be even cheaper, since you can get them quite inexpensively from an antique shop. But a jointer plane will take some practice to do this job well.)

You could use a router set in a router table, with a crosscut sled set at 45 degrees.

Building a jig with a "pin" that fits into the previously cut groove, will make sure all the grooves are cut an equal distance apart. The "pin" will be attached to the sled in some way, and will sit against the edge of the work piece for the first cut. After the first cut, the "pin" will sit in the groove produced by the first cut. The board is then lifted and moved, so that the "pin" sits in the most recently cut groove. This process is repeated the length of the work piece.

I'd make a jig similar to this.