Rainbow Blaster




About: There are some things you should just never, never, do...

Rainbow Blaster

I had the idea to make a hand-held device to 'squirt' Holi powder. After a little experimenting the Rainbow Blaster was born!

The device consists of 5 plastic squeeze dispenser bottles that have siphon tubes (straws) added inside them to pick up the powder from the bottom of the bottles. They are all pneumatically connected together back to a can of duster spray. When the duster spray trigger is squeezed the spray pressurizes the bottles and up and away goes the powder!

It's fun to go around puffing out little rainbows! Never mind the 'damage' it could do to an unsuspecting person. (Evil laugh!)

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Step 1: Materials & Tools


Dispenser Bottle

Silicone Aquarium Tubing

1/4" Barbed Tee (Drip Irrigation)

Spray Duster

Holi Powder

Plastic flexible straw (1/4", 6mm dia. / Not shown)

Cardboard Box (Not shown)

Packing Tape (Not shown)



9/64th drill bit

Drill motor

Utility Knife

Step 2: Install Tee Onto Bottle Cap

Install the tee into the cap of the dispenser bottle.

Drill a 9/32" hole between the base of the nozzle and the bottle wall that you can see through the cap. Align the hole so that it is opposite the cap lanyard.

This hole is somewhat smaller than the tee, but the tee can be forced into place and seals well.

Step 3: Add Syphon Tubes

The syphon tube pulls the powder up from the bottom of the bottle and ejects it from the nozzle.

Unscrew the cap and insert a straw (syphon tube) into the nozzle. To get it to fit into the nozzle the straw can be creased. The straw is pushed up into the nozzle until it is snug. In my case that was to within about a half-inch of the tip.

I bent the bottom flexible end of the straw so it would pick up the powder from the perimeter of the bottle since I knew I would have the device tilted in operation. Trim the straw so that the opening almost hits the wall of the bottle.

Orient the pick-up bend so that the opening is opposite the tee as the bottle will be tilted with the tee high and the straw opening low.

Install straws as syphon tubes for each color dispenser.

Step 4: Add Powder

Carefully add Holi powder to the dispenser bottles. I only filled the bottles about 3/4" full as that is all I could spare. You should be able to nearly fill them up if you want to.

The powder is very fine and can get everywhere so you might want to do this outside.

[You might want to take note to only use the Rainbow Blaster outside as I can only imagine what a mess it would make if discharged inside. You have been warned!]

Step 5: Connect to the Duster

The connection to the duster can output is press fit. I was very lucky that the inside diameter of the tee was the same size as the outside diameter of the duster spray tube.

I cut the spray tube to about 1" in length and then pressed the spray tube onto the valve of the duster and then pressed the tee onto the spray tube. Ta-da, a connection for tubing on a can of duster spray!

Step 6: Create Support System

My support system is a cardboard box. I took an 11 x 9 x 4 inch cardboard box and taped all gaps closed. I then cut a 2-3/4" wide slot down the long side for the dispenser bottles. The bottles just fit. (I wish the box was 11-1/4" as it was really just a bit too tight. But it did work.)

Behind the bottles I traced the outline of the duster can and cut an opening for it. I taped the can to the box so it would not come out. I added cardboard and newsprint inside the box as needed to get the can into the position I wanted.

Step 7: Connect the Duster to the Dispensers

I used silicone aquarium tubing to make the connections from the duster tee to the dispenser bottles. The silicone tubing was more flexible than vinyl tubing which made it easier to get it over the barbs on the tees.

The bottles are fed from both sides -- just for good measure (and I could use just tees to make all the connections ;-).

Step 8: Blast Rainbows to Your Heart's Content

You are done! Now take this Rainbow Blaster contraption outside and start blasting some rainbows!

(Rainbows come out in puffs - so you have to give a little shake between each blast to get the powder into position for the next puff)


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    15 Discussions


    Tip 1 year ago

    Maybe a smaller version of this could be mounted to an RC plane.

    1 reply

    1 year ago


    Did you try other ways to get the powder out? I'm thinking something like a venturi effect, the way an airbrush or sandblaster usually work. Possibly routing the air to the bottom of the bottle to blow the powder out may help reduce the amount of shaking between puffs.

    1 reply

    Reply 1 year ago

    Thanks for the comment and suggestions.

    I had wanted it to produce clouds of powder continuously, but it just didn't. I think it may be that the powder around the opening in the syphon tube gets blown out and then there is just a void around the syphon tube opening. I like your ideas, but think that they may still have the same problem of the immediate powder getting blown out and then a void. It may be because the powder is so fine.

    Perhaps I should invert the dispenser bottles to have gravity help the powder flow and put the tee in the tip of the nozzle and use the venturi effect to shoot out the powder that would naturally fall down into the air stream. Lots to consider.


    1 year ago

    First of all, have the comments section changed?



    1 reply

    1 year ago

    OH MY GOD!!!!!!! it's happening... jalopnik ran an article about the hypothetical Prius version of rolling coal a few years back and someone finally found a way to make it a reality!

    original article:


    1 reply

    Reply 1 year ago

    LOL - Thanks for the comment! Glad to give the anti-Rolling Coal activists an option.:-)