Foundation should come first so I think we should start with the leg. The leg I use has a oval hole in it and a 1/2″ hole through the upper part for the bole that holds the bench together. The bolt threads into an insert cast into the bottom of the bench top. (Mold shown below.)

There are bench leg molds available but I have not seen any with this connecting feature. You might want to design and build your own and make it more personal. The concrete I use is Quickrete and I add a little Portland cement. (about 2 pounds per 80 pounds of Quickrete). It makes it a bit stronger and easier to finish.

I hope this enough to start. We will get to the bench top mold next.

Antique concrete bench leg mold

Antique concrete bench leg mold

The mold after it has been filled with concrete - with threaded pipe used to connect leg to top.

The mold after it has been filled with concrete - with pipe temporarily installed. The pipe will be pulled out just before the concrete sets, and the resulting channel will be used for the connecting bolt that holds the finished leg to the top of the concrete bench.

Installing the bolts in the top so it can be connected to the leg.

Installing the bolts in the top so it can be connected to the leg.

Connecting the top to the molded leg for safety.

Connecting the top to the molded leg for safety.