The giant rainbow water blob is the ultimate summer-time experience that will keep all ages laughing and having fun for hours! You can roll on it, slide on it, swing onto it, run on it, lay on it, or even take a nap on it!

The giant rainbow blob is created from one large plastic bubble that is then further divided into 6 sections, one for each color of the rainbow.

For this project you will need a large, heavy-duty sheet of plastic. I used a 20’ x 25’ sheet that I purchased in the paint section of my local hardware store.

You will also need parchment paper, an iron, cardboard or a wood slab, scissors, sharpie, measuring device, duct tape, food coloring, and a water hose with a water source.

Clear a large area to work on your water blob, and fold your plastic sheet in half.

Step 1: Parchment Paper Protection, & Sealing the Perimeter and Rainbow Sections With a HOT Iron

The first step is to seal the perimeter of your folded plastic with a hot iron. Since the plastic sheet is folded in half, this means you will only have to seal three sides to make your initial "bubble". Parchment paper is used to protect the iron and the surface you are working on from melted plastic. The goal is to melt the folded plastic together by running the iron over it at a slow and steady pace. If you move the iron too fast, the plastic sheets will not melt together completely. If you move the iron too slow, the melted plastic will shrivel up too much, and become brittle and more susceptible to holes.

Tear a three-foot length of parchment paper and fold it in half long-ways. Measure in about 2-3 inches from the crease of the parchment paper. Use the sharpie and a straight edge to draw a line along the crease of the parchment paper. This will serve as your guide to run your iron along

Starting at one corner, put your wood slab or cardboard underneath the plastic. Sandwich the plastic in between the parchment paper so that the plastic edge butts up to the parchment paper crease.

Put your iron on high setting. Move the iron along the parchment paper using the black sharpie line as your guide. You will need to experiment with the speed at which you move the iron. I found that moving at around ½ inch per second melted the plastic together consistently.

Move the parchment paper up as you iron around the perimeter of the plastic sheet.

When you are done, divide your giant bubble into 6 even columns. To do this, take the length of one side of your blob and divide it by 6. This is how wide each of your 6 rainbow sections will be. Mark the columns with your sharpie.

Starting with your first section, put a piece of parchment paper underneath the plastic where you drew your section divider, and another piece on top. Use your iron to slowly iron down the length of each column. Do this for each of the 5 section dividers to give you a total of 6 sections.

Step 2: Adding Color and Filling the Sections

Now it’s time to fill your giant rainbow water blob with water!

Transport your plastic to your site, and inspect the ground for any sharp sticks or rocks that might damage your bubble blob. Carefully lay your deflated blob out where you want to fill it. If you don’t have soft grass, you may want to put a tarp underneath the plastic.

Use your scissors to make a small hole at the top of each column. Fill each with 1-2 bottles of gel food coloring in the order of a rainbow. You can also add a little glycerine to each section if you want.

Get your water hose and place it deep into your first water blob section. Fill it up. As it fills, use your hand to guide out any large air bubbles. Once a section is filled, remove the hose. Have someone lift the section of the plastic where the hole is up so that water does not escape. Use a piece of duct tape to patch up the hole.

Move to your next section, and repeat the filling process.

Step 3: Inspect and Enjoy!

Once you are done, gently lay on each section and inspect to see if there are any leaks. If you find a small hole, patch it with duct tape.

You may also try adding a little baby oil to your rainbow blob to make it slippery and more like a slip-and-slide.

Your giant rainbow water blob is also really cool at night if you shine some landscaping lights on it, or use a flashlight to illuminate the colored water within!

Lastly, keep in mind that your giant rainbow water blob is not made of iron. It is a delicate, kind, and ephemeral being, much like a real rainbow. Don't get too upset if one or more sections break, and the colored water begins to gush out like a raging river. That too can be part of the rainbow blob fun. And think of all the lovely plant life downstream that gets to enjoy the water from the rainbow blob as well! Your giant rainbow blob will not last forever, but the memories you make from constructing and playing on it will.

Happy blobbing!