|The umbrella stand in all its glory|
The umbrella stand consists of a cheap planter base, 1" PVC pipe, and ~35lbs of concrete (from a 60lbs bag), for a total of ~$11. I punched a hole in the planter, shoved the PVC pipe though, and sealed the hole with hot glue. This was followed with a liberal application of WD-40 to all of the surfaces of the mold.
I mixed the concrete in a 5Gal bucket with my shovel, as the hand trowel didn't have the necessary oomph, and ended up adding more than the minimum amount of water in order to reach the right consistency.
Next up was to pour the concrete into the mold, which was placed on top of an old wine crate, allowing the PVC pipe to extend past the mold. The concrete was shaken after pouring to settle it, a necessary step that still left me with some "worm holes" in the surface. I'm not complaining. It adds "character". I also smoothed the "underside" of the concrete with a 2x4, getting as level a surface as I could. The WD-40, mentioned above, acts as a lubricant, allowing for the clean separation of the concrete from the mold once dry.
All was left to do was to wait. Concrete takes four to five days to cure and needs to remain damp during the process, so I covered the whole thing with saran wrap. Four days later and the concrete was dry, slipping out of the mold easily.
Shake the concrete mold more. I'm guessing a more vigorous shake would reduce the "worm holes" and leave a smooth surface all around.
Add "weep holes" to the mold, allowing excess water to escape from the bottom of the mold. I did this after the fact, but was only able to add weep holes to the side instead of the absolute bottom.
I'm looking forward to doing more concrete molds. The setup is cheap, the process simple, and the results are pretty cool!