Build your own wood beam mantel for just $35 of lumber. If you have some wood stains lying around that may be all you spend!

Materials

2x common wood boards - 1"x10"x6' (or however long you need it)
1x common wood board - 1"x8"x8' (the extra 2' length is for the sides)
wood conditioner (or a damp cloth if you're thrifty, google it)
wood stain
wood putty
optional Danish Oil for a bit more sheen

Tools

table saw or circular saw to cut 45 degree miter angles along the long edges.
chop saw or a miter box and handsaw to make the shorter cross cuts
various distressing tools - get creative!
- chisel
- something stabby
- chain
- box knife
finish nail gun

Step 1: Cuts

The 1x10's will act as the top and bottom of your mantel.

Cut both 1x10's to your preferred mantel length using a 45 degree miter on both short ends and one long end. All miter slopes should start from the same face (see pic)

The longer 1x8 will be the front and the extra length will also account for the side end caps.

Cut the miter angles out of both long ends of the 1x8 face board
Cut off the sides of the mantel from the extra length of the face board. They should match the depth of the 1x10s
Finish up by cutting your face plate down to size with miters. This is the only piece that will have all 4 sides mitered.

Step 2: Distress

This is the part that I enjoy most. I still experiment every time I build something so don't be afraid to try new things.

A couple of methods I used are:

worm holes
gouges
screw scratches
cracks/splits

But you can use a hammer claw, chain, wire brush, or anything you dream up. Check out the notes on the pictures for more details.

Step 3: Stain

Follow the instructions on the can. Wipe on. Wipe off Daniel san.

I forgot to take a picture here. It's important to note that with these cheap soft woods, the grain can take stain differently leaving you with a zebra striped project. You really need to pre-condition the wood with a damp cloth wipe or use the linked wood conditioner to open up the wood to accept stain more uniformly.

Step 4: Nail It Together

I used a finish nailer with 18ga 1.25" nails. Make a 5 sided box.

Step 5: Edge Distressing

So far we have a beat up box. It looks pretty good, but it's not fooling anyone. Carve out random patterns off the edges. It brings all the plates together and makes it look more like a solid beam.

Sand, fill with wood putty, re-stain.