Aqua Pen - Water Prank Pen

Aqua Pen continues the water-spraying prank series with a new everyday object - this time, a pen. It may look like a simple writing tool, but instead of only sitting on a desk, it hides a small water spray mechanism inside.

The design is simple to print and assemble, with all printed parts intended for PLA. Just like Aqua Lighter, it is based on a real spray atomizer placed inside the body, while the top button acts as the spray trigger and mimics the click button of a regular pen.

As with the previous models, Aqua Pen still requires a small spray atomizer. I recommend using one from a 30ml spray bottle, as this size tends to work best. Keep in mind that atomizers are not well standardized, so depending on the source, small fit adjustments may still be needed.

This model comes in two variants: Dummy Pen and Inkless Pen. The Dummy version is fully printed and focused purely on the prank function, while the Inkless version includes a front section designed for an inkless pencil tip, giving it a more realistic pen-like feel.

Materials

• Body, tip, button: PLA
• Spray atomizer: salvaged from a small spray bottle

Atomizer Dimensions

30ml spray bottle reference (dimensions may vary):

Assembly Guide

Step-by-step instructions for preparing the atomizer and assembling the model.

Before assembly, compare your atomizer with the dimensions shown in the infographic. Small differences between spray bottle models can affect the fit.

Disassemble the Spray Bottle

Remove the nozzle cap and take out the spray head (button + nozzle).
Then remove the sealing insert from inside the cap.

This will expose the atomizer assembly for further extraction.

Extract the Atomizer

Carefully cut the plastic cap using side cutters to release the atomizer.

After removal, check the length of both tubes (top and bottom).
Trim them if necessary to match the expected proportions.

Prepare Printed Parts

Remove the brim from the pen body and clean the top edge with a deburring tool.

Final Assembly

Insert the atomizer into the pen body and push it all the way down until it is fully seated.

Press the button onto the top tube. You may need to push it a few times to make sure it sits properly and activates the atomizer correctly.

Screw the front tip into the pen body.

For the Inkless Pen variant, screw the inkless pencil tip into the front section.

Done.