Cut the woods
I used my circular saw to cut the 2x4s and the 2x10 to length.
cut the notches in the pieces of 2x10
I used a jigsaw to cut notches in the pieces of 2x10
Sand the pieces
I set my orbital sander to sand the pieces of wood.
Stain the wood
I stained the wood with Varathane Wood Stain in “Sunbleeched” and really like how it gave the wood a modern grey look. This is just to get a base coat and I will have to touch up the stain after assembling the base.
Assemble the base
I used 2.5” long finnish screws to assemble the base.
fill in the screw holes
I used wood putty to cover up the screw heads and then sanded putty once it had dried. I then added a 2nd coat of stain.
Making the mold
I used some scraps of ¼” thick plywood and my hot glue gun to make a template for the concrete top. I want the countertop to overhang the base by an even amount so making a template is a good idea. I ripped 3-1/2” wide strips of ¾” thick melamine on my table saw. I used the template that I made to measure the lengths for the side pieces of the mold before cutting the pieces with my miter saw. I placed the pieces around the template and then glued them down along the outside of the mold with my hot glue gun. I glued down a few scrap pieces of 2x4 for additional support. I sealed the inside of the mold with silicone.
Making the plywood core
I cut 2 pieces of plywood to fit inside the mold with about 1-1/2” of between them and the walls of the mold. I glued and screwed these pieces together before sealing them with minwax polycrylic. I sealed them so that they will not suck water away from the concrete as it cures. I cut a piece of steel mesh with wire cutters and then used screws and wire to suspend it about ½” from the surface of the plywood.
mix and pour the concrete
I suspended the plywood core on some strips of plywood so that I would have a way to keep it level to the surface of the mold. I mixed and poured two bags of Quikrete 5000. I used a hoe to push the wet concrete down to the bottom of the mold. Once the mold was about three quarters of the way full I placed the plywood core and then filled in around the edges with wet concrete. The plywood core kept floating up so I used some weights to hold it down. I vibrated the mold with an orbital sander with no pad to try and get as many air bubles as possible.
Remove the slab from the mold. I let the concrete cure 4 full days before removing it from the mold and placing it on the base.