I was planning to use a Mantle like slab of wood to make a wide shelf to use as a computer desk.
I have access to 4" x 24" Yellow Birch, but It was cut this summer, so it probably isn't dry enough yet. I also have access to some old 2 or 3" Oak planksThat might be better for this purpose.
I am wondering what would be the best way to hang these.
It will be going into a corner. throught the walls are finished drywall to the side, and a closet behind.
I'd prefer the look of it just kind of being out there, without a leg or massive bracket, but I cant really picture a good way to do that with existing finished walls.
You can mount a floating mantle with the walls finished, it just limits the options. You can use long lag bolts screwed into the studs projected out of the wall. Drill holes into the mantle that will accept the projected bolt heads. Mix up epoxy and place the mixture in the holes. Mount the mantle and support the load until the epoxy sets.