This is a super simple project that has been a huge hit. Here's a quick overview. Check it.

Our nephew wanted a TechDeck half-pipe for his birthday this year. We thought we'd kick it up and build him his very own real concrete fingerboard bowl park. The goal was to create a unique park from materials we had on hand. At 60 lbs., this park weighs a wee bit more than our nephew.

Materials:
tub/form (we used scrap 3/4" plywood and spray glued some plastic film to it)
bowl(s)
caulking
styrofoam
ready-mix concrete
spray silicone or some type of mold release
and of course, duct tape

Step 1: 1. Create the Form

Create a negative mold of your desired park shape.

We built a tub from scrap 3/4 plywood and spray glued some plastic film to it. To create the bowl shapes, we used 1 larger wooden bowl and 2 smaller glass bowls. The transitions/gaps where shaped from a few chunks of styrofoam and duct tape.

Note: The mold needs to be smooth, so the concrete can release when cured.

We used caulking to make smooth transitions and rounded corners. Use your finger and a little water to smooth out generous beads/globs of caulking. Let the caulking dry overnight before pouring concrete.

Step 2: 2. Pour Concrete

Mix and pour the ready-mix concrete.

We used a full 60lb. bag of basic post concrete mix since we had that on hand. It worked ok, but cracked because the form was too thin (specs state minimum of 2" thick). The trick to a smooth final finish to knock all of the air bubbles out. We tamped everything well with a small stick. Then we beat on the outside of the form with a hammer. You will see the bubbles rise to the surface. Let sit for at least 24 hours. (we rushed it and cracked the main bowl. as an easy fix, we glued the pieces to plywood with liquid nailsback in business)

Step 3: 3. Remove Form

Carefully remove your form. If you have any cracks or bubbles, fill with non-sanded grout or other concrete patch/filler.

Add the finishing details like:
-stickers
-coping
-rails
-extensions
-etc

Step 4: 4. Shred!

"Cannon Ball Park" in action:

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59 Comments

Ben DangerH

6 years ago

I love this, inspired

danx_the_drummer

10 years ago on Step 3

that is for play with Beyblades YA-HA!!!!

PotatoCoffee

11 years ago on Introduction

Very good job, Nice deck!

reref

11 years ago on Introduction

Nice one. Five stars!

dylankunaikennedy

11 years ago on Introduction

did you make the banana board tech deck or buy it? plz respond

Sakrete

12 years ago on Step 2

Excellent Instructable. Great choice of Concrete :)

tech deck123

12 years ago on Introduction

awsome looooool

splatman

12 years ago on Introduction

Reinforcing it with mesh would help. Use poultry netting or hardware cloth, shaped to follow the contours on top. When pouring the concrete, make sure the mesh/netting is not in contact w/ the mold, so it won't show in the finished product.
Another layer of mesh along the bottom, and/or some rods, to reinforce it from the bottom as well.
One way to use less 'crete, (and make it lighter too,) is hide chunks of Styrofoam in the thick parts. Just make sure they don't surface when you tap the mold during the air-purge routine. Tying them to the mesh may help. Another way is to screw small boards across the top of the mold, with legs holding down the Styro-chunks thru the 'crete. When done air-purging, unscrew said boards, remove the legs, and fill in their "footprints".
Or let the Styro-chunks surface (cut holes the bottom re-mesh for this), and remove them after the 'crete's set.
If you wish to reduce the amount of 'crete needed (or get more volume), but don't care about weight, use rocks from your backyard in place of the "Styro-chunks".

You can make your concrete a different color by using pigment. Pigment may be pricey, so you may want to leave that out.
http://www.directcolors.com/concretepigment/
or buy it at a hardware store.