Hey everyone. I haven’t been on here much, but that doesn’t mean I haven’t been busy slinging!

Ok, this is very much a work in progress, but I just cobbled together a sling bullet with a built-in motion sensor. It provides 3-axis acceleration, gyroscope, and magnetometer data. All in its about $30 worth of stuff mostly from Adafruit. If anyone wants to build their own, let me know.

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Whoa! Very cool. Will be very interesting to see what sort of data you get off of it!

Not sure I'm ready yet to dive into that level of detail myself :D too much other random stuff to test first!

Oh very nice. I don't plan on replicating it, but I would like a schematic or at least the numbers of the parts you used.

Amazing! :thumb:

Ditto:  Amazing!

I could rustle up a 3D printed housing for you ;)

irgendeinekiwi wrote on Mar 17^th, 2026 at 4:52pm:

I could rustle up a 3D printed housing for you ;)

Thanks! I could crank something out on my printer pretty easily too, but I’m much more comfortable using foam around the lipo battery! The best thing to do would be to design a custom PCB with a coin cell holder on it, upgrade the microcontroller to an esp32 for wireless data transfers, and then integrate the whole thing into a balanced glande with extra ballast… but I wanted to prove out the concept with what I had lying around first :D

Minor update: threw a snap-together biconical housing together… major improvement in the packaging!

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Does it transmit telemetry data?

irgendeinekiwi wrote on Mar 24^th, 2026 at 7:46pm:

Does it transmit telemetry data?

Unfortunately this version does not. This is literally a bunch of leftover electronics that I found lying around, and I definitely would not have chosen all of these components if I was designing something from scratch and willing to pay for parts. You have to download the data from internal memory using a serial terminal… super clunky and difficult to use, but it was 100% free because I already had all the parts!

NooneOfConsequence wrote on Mar 24^th, 2026 at 4:18pm:

Minor update: threw a snap-together biconical housing together… major improvement in the packaging!

Do you have an STL? Have you considered a think 100% infill TPU shell? This could offer MUCH more durability.

BensBestBentWire wrote on Apr 13^th, 2026 at 10:01am:

NooneOfConsequence wrote on Mar 24th, 2026 at 4:18pm: Minor update: threw a snap-together biconical housing together… major improvement in the packaging! Do you have an STL? Have you considered a think 100% infill TPU shell? This could offer MUCH more durability.

You may be solving the wrong problem here. Durability is not the issue. The logger survives and collects data just fine… but the accelerometer is only good up to 16G’s, so it maxes out as soon as it leaves the sling pouch and the data is useless during past the release point.

But of course if you want an stl for the 3d printed shell I can get it to you. I actually have one version that has a tight snap fit and a second version that is looser so you can deploy payloads from the shell mid-flight… but I’m still working out the kinks on that use-case.

Good to know. I am totally still interested in any stls you have for this

I want to know how the stability of a glans degrades during flight. How soon into its flight would a 45 gram lead glans lose its rifle spin and start to tumble? What have you been able to find with your electronic glans?