How to Make a Flat Pack Sandbox or Paddling Pool

Ever had to store your sandbox or paddling pool when the weather isn't nice anymore? Didn't have enough space in you garage? Here is the solution!

With this sandbox or paddling pool made out of a sheet of polyethylene, you will never have this problem again. You can easily disassemble the sandbox and put the sheet of PE away behind a rack or closet.

Fun guaranteed with this sanbox or paddling pool!

Step 1: Materials and Tools

The size of the materials you use depends on how big you want to make the sanbox. I would recommend to not make it to big because te structure could lose some strength. My sandbox was just big enough for a small child because it was hard to find a bigger sheet. You can use my template and scale it to every size you want.

• First of all you need a sheet of polyethylene. Make sure it is large and thick enough (I used a 1 by 2 meter sheet of 4mm thick).
• You also need a plate of MDF to put underneath the sheet of PE when you cut it so you don't damage your floor. You also need a piece big enough to make a guide for your milling machine. (I used a plate from 1m50 by 2m40 and cut it to a square of 1m50 by 1m50 so I could use the rest for my guide).
• Next you need a router and a router bit. I used a router bit that makes a slot of 10mm. If you choose to use thicker plate you will need a wider one so you can fold you PE without a problem.
• You will need a tilting saw to cut your guide.
• I also used a dremel to cut some pieces out and for some finising touches.
• You can use a fine marker to make your sketch and a thick marker to mark your final drawing.
• To draw the long lines you need a long ruler. you can also use a protractor for straight angles and a tape measure.
• You will also need some nails and screws to hold your piece in it's place. It doesn't really matter which size they are.
• To fix the corners of the sanbox together I used 3 bolts and wingnuts. You cold use something else if you want.
• You will also need a hammer to beat the nails and some pliers to get them back out.
• I also used a hand drill to put the screws in.

If you want you can have this design cut out with a CNC milling machine for a better and cleaner result.

To make this sanbox you will also need this template:

Step 2: Prepare Workplace

Make sure you've got a large space so you can move around freely. If you decide to work outside, swipe first so there isn't anything in the way.

Now you've got a nice space you can put your MDF panel down and your sheet of PE on top. It is also easy to have a table nearby so you can put all your tools here.

Step 3: Making Guide

To make this sandbox you will need a specific form to guide your milling machine. This is a bow with a ray as long as one side of the largest triangle (see template). This depends on the size of your PE, I made it as long as my smallest side.

You just mark where the center of your circle will be, now take the tape measure and mark multiple points on where the circle will be (so with me this was on 1m) now you can connect these points with your marker and saw this bow out with the tilting saw.

It's important you know you will be putting the guide on the outside of the cutting line. So make sure this piece is the best (upper piece on the picture)

Step 4: Drawing Template on PE

Now draw the triangles as seen on the template with your fine. you can use the guide to draw the bows. Use the thick marker to show the final drawing.

Step 5: Milling Slots

First you need to know the distance between the center of your router bit and the round side of you milling machine. You can just measure this with your tape measure. (On my macine it was 8,5cm)

You can fix your piece with some nails so it doesn't move when you're milling. You will need to mover the nails if they are in the way for your guide or milling machine so you can use the tweezers to get them out.

You will start milling the bows so with your tape measure you can draw some lines where the guide will need to be (distance = what you measured on the machine). You can now put your guide on these lines and screw them to the mdf and PE.

Before you start milling you need to test how deep you want to make your slots. I tested on an extra piece of PE and chose slots of 2,5mm.

Now you put your milling machine (set to the right milling depth) against the guide and mill out the slots. (At one point my routing bit got loose so it went through the piece, so make sure you tighten it enough!)

With the same technique you can mill the straight pieces as well. (the order in which you mill the pieces out doesn't really matter, I just chose what I thought would be the easiest)

Step 6: Milling Contours

I used the same technique as in the previous step to mill out the contours. The only difference is the milling depth which should be the same as the thickness of your PE. (I chose to mill this in two times, once with a depth of 2mm and once with 4mm so the cut coult be cleaner).

To cut out the smaller part I used my dremel. I also sanded some corners off and drilled holes to put the sandbox together (see template).

Step 7: Putting Sandbox Together

Now you need to fold the PE and put the piece together with the bolts and winged nuts. If you have any lines from the markers left you can use some nailpolish remover or aceton to remove these. If you have any sharp corners left you can still sand these away or use your dremel.

Step 8: Enjoy!

Now you just need to add sand or water and you can enjoy your sanbox or paddling pool!