The Hygrometer (AQI BOARD)

June 06, 2026

The Hygrometer (AQI BOARD)

Play "Mirage" by "Creepy Nuts" to see this post.

Man, getting a 110mm glass piece is not easy. Goddamn. So I ended up making it 125mm.

Youtube video of the real thing: Hygrometer

This project is on Instagram highlights by "\ h.l_Kal /" on @ro_h_bots

Github Page for this will be updated soon.

Anyways, we have it here. The GREATEST hygrometer you will ever need for your 3D printer filament storage box—or better yet, for my room.

This one was made to look extraordinarily beautiful in my room on a board which will house:

Hygrometer
Thermometer
AQI Meter
VOC Meter

Here's the interactive 3D of it. I am impressed by the rendering of the glass on it as well! I hope you can load it. That glass was hard to model and adjust for this web graphics model.

An Interactive 3D View of The Full System Assembly

(Electronics Omitted)

The Face

So the face as shown below was a result of the inspiration I got from 3D printed letters and my black Posca markers. I made them in Hindi letters because they simply look beautiful.

The printing process was straightforward. Pause the print at the defined layer and paint the entire surface, minding the sides to make sure the letters can be visible as black from the gaps that the printer creates.

Now comes the gears and the tick. I was heavily motivated to create something beautiful that moves and something which is visible on the face. So I chose this gear set and made that tick style. I used brass rods (1mm) purely for aesthetic purposes.

Face With Tick Gear System

The Body

There was a problem with the body from the beginning. It was the glass. I made the face 110mm and then realized it was just impossible to find a 110mm dome watch glass. I found a 125mm very easily, so I remodeled the face to be embedded on a "top housing" as shown below.

The body is 3 parts: the "top_housing," "bottom_housing," and a "battery_cover." The top housing is attached with several M2 bolts to the bottom one, which has nuts embedded into it. The bottom housing also has magnets embedded for battery cover attachment and bigger ones for making the whole device attach itself to any ferrous surface. The red surfaces are shown differently to indicate the manufacturing process as seen below in the "Maufacturing" section.

The battery cover is special. I made it using washers because I ran out of 1mm thin magnets. It worked like a charm.

Bottom Housing

The Insides

The insides of this device is pretty straightforward: an N20 micro DC motor with an industry-standard gearbox attached to a globoid gear set. The electronics consisted of a DRV8833, ESP32-C3, AS5600, and an SHT40.

The battery system was an afterthought. The entire device is supposed to be powered using the magnetic pogo pins on the back, as it is meant to be mounted on the wall. The battery system was included so it can be taken briefly to different places to measure the humidity of various sites.

Manufacturing

Now this part is quite complicated, so stay with me here. All the parts are shown with the 3D printer build plate so there should be no confusion.

First, let's start with the top part. The top consists of the face, the tick and gear subassembly, the motor subassembly, the AS5600 bracket, and the top housing itself. All these parts can be printed in a straightforward way, except the face, which is described above.

The bottom part is, however, very difficult to print. The "bottom_housing" has to be paused four times during printing to embed things. Below in the slide, you can see all the pauses and the embeds exploding out in the interactive 3D models.

1st Pause: This was to embed the back mesh directly into the print. A little B7000 was used as an improvised adhesive to make sure both sides of the mesh were attached. HOWEVER, there's a catch! Observe the red part on the slide; that red part has to be preprinted. In fact, all the red parts have to be printed before starting the print of the "bottom housing." The red part on the slide is used as a stencil to cut the mesh into the exact required shape. I used a little glue on the red part to attach it to the mesh and then traced an outline; this way, I end up with a clean-cut mesh. It looks very professional as well. The yellow layer is glue spread lightly.
2nd Pause: Well, well, well! This part is very complicated. There is now a blue part as well. That is a model-in-place 3D printed support structure. That means it is supposed to be printed as a support. The point of this pause-embed is to make sure the battery cover interfacing layer has a build plate texture, so we use a red part in the same way. We pre-print the red part and glue it in place on the support structure very lightly so the interfacing layer has a build plate texture. The special thing about B7000 is that it comes off very easily and does not stick to the PETG part that easily, so it acts like honey, keeping the part in place while the printer prints on top of it. The Swigly glue application(Yellow thing) is shown to show you that real world application of the glue.
3rd Pause: This pause is simple. Take your magnets and insert them; I always use a dab of glue to drench the magnets inside their holes. The glue is optional here so not shown.
4th Pause: Complicated again. Insert the nuts first normally. Then take all the red pre-printed parts and glue them in place with ever-so-slightly applied glue on top of the embedded nuts. Repeat that for all holes and then click unpause. Don't just insert one and call it done. Pay special attention to the glue application (Yellow thing). You need two miniscule dots of it.

Bottom Housing 1st Pause

That's it! I hope you liked the designs, and don't forget to comment below if you have something to say about this device.

Have a nice day

-Rohit

Made in Rudra, India by RolandThsive

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