Step 1: Melamine Mold and Pour

The sides are fairly straight forward..Cut and assemble.

The center dividers and bottom piece were copied from a shaped template by using a laminate trimmer with a bearing bit.

The shaped inner walls were bent into place using bender ply, screws, clamps and a lot of patience.

Insert the the shaped dividers to keep it all together and add a little hot glue

All corners were sealed with silicone.

The Pour:

Sorry no pics as I was elbow deep in black GFRC.

Once you have properly blended said mixture [ it should be the consistency of clay ] its off to the races.Hand packing the bottom first and then up the sides.. I had made shaped 2" foam to be stacked and placed inside the GFRC sides. These were needed to support the last layer as we topped out . We tried for 1/2" to 3/4" wall thickness everywhere. Troweling the top layer flat. This mixture gets hot so when you have a closed form like this you need to provide a way to vent the internal pressure. I tried pin holes ..not enough and ended with a somewhat distorted top surface.

Step 2: Demolding

Next day I carefully removed the sides
Pulled out the shaped dividers and voila!

Step 3: WET POLISHING

Not sure if the time was well spent here. Wrestling around with a wet 70 pound piece was a challenge. Went thru the grits with a wet polisher to mellow out the lumps created by the expanding trapped air.The inner surfaces were worked with diamond hand pads and abraded knuckles ..Kept flipping it around until I had enough.. The vertical sides were hard to keep clean as the slurry would run down and leave a stain on the polished surface. Next time!