(2) Cardboard Tubes (best with foil or plastic linings for water resistance)
(4) 1" Screws
Clear Packing Tape
Thin Foam Wrap (a packing / shipping material)
Sacked Concrete / Rapid Set (if you're in a hurry, although it tends to wash out colors)
CHENG Pro-Formula Mix
Tin Snips / Wire cutters
Long Needle Nose Pliers
Phillips Screw Driver ( + )
Weights / Rocks / Sand
Diamond Sanding Pad / Sandpaper
Step 1: Prepare Tubes
The largest tube will become the outside form. In this case it's about 5" diameter and 9" tall (it contained coffee grounds). The inside tube is about 4" x 7" (shredded potato chip container). This means the wall thickness is only about 1/2" - do not go any thinner, this is already pushing the limits.
1. Starting with the Interior form, trace the diameter on a piece of thin foam padding (this is usually used for packing / shipping). The idea is to tape a circle of foam to the base so when we go to de-mold that metal ring isn't trapped down inside.
2. After the foam circle is taped to the base, cut a ~2" foam strip to wrap and tape around the bottom edge (to keep that ring from getting trapped).
3. Screw the (4) 1" screws into the top of the Interior form. The screws should rest on the lip of the Outer cylinder, helping to keep it lined up during the pour.
4. Clean up the forms, Inside and Out and remove any oils or residue with denatured alcohol. If you don't clean the containers out, you'll see it on the surface of the finished concrete for sure.