V2 Magnet Injection Assist for Insulin GLP-1 TRT

Easier and pain-free self injections:

Injecting myself makes me anxious.  This device takes away most of the stress by giving me an ergonomic grip on the syringe and automating the injection motion with magnets.

After adding the syringe, push up the sled until the embedded magnets snap it into place.  While holding the guide against your skin, push down gently on the actuator and the sled will smoothly jump to the lower set of magnets while inserting the needle.  The syringe plunger will be within easy reach without adjusting your grip.

What's NEW in V2?

• Significantly reduced sliding friction thanks to new filament rails and improved tolerances
• Simplified hardware needs: now just one type of screw and fewer magnets
• Longer travel and streamlined options - 2 sizes (down from 3 in v1) with no downsides or loss of compatibility
• Simplified assembly and perfected tolerances.
• Dozens of other small tweaks and improvements

• Compatibility with the accessory 'Vial Drawing Assist' which aids in drawing your medications from a vial into syringes

  

Syringe Compatibility:

Pick a body based on needle length and desired injection angle:

• Standard Height body is compatible with 5mm, 8mm, 12.7mm,  or 16mm needles (3/16" - 5/8")
• “Tall” body supports longer needles up to 38mm or 1.5"

Syringe adapters available:

• 0.3ml U-100 syringes
• 0.5ml U-100 syringes
• 1ml U-100 syringes
• 1ml Luer Lock syringes
• 1ml BD brand Luer Lock syringes (not as common.  Barrel is shorter and wider)
• 2ml BD Emerald Luer Slip syringes
• 3ml Luer Lock syringes

Common uses are Insulin, GLP-1 (Semaglutide / Tirzepatide), TRT (testosterone / hormone replacement therapy), or B-12 injections.

Printing and assembly:

Total assembly takes less than 5 minutes.  All magnets are press-fit and shouldn't need any glue

1. Print all parts as oriented in the files. You will need:
   1. One Body (depending on the length of the needles you use and straight or 45° angle)
   2. One Sled
   3. One Syringe Adapter
   4. One Plunger
2. Sled Assembly:
   1. Press in 3 magnets.  2 on the rear and 1 on the bottom. (take care that all three magnets polarity are facing the same direction)
   2. Slide in stainless dowels from the top
   3. Attach the Syringe Adapter using 2 M3x6mm screws
   4. Attach the Plunger to the top of the sled using the last M3x6mm screw.
3. Body Assembly:
   1. Add 2 short lengths of filament to the back.  You can insert them fully then just cut them flush at the top.
   2. Press in 2 magnets.  The polarity should be aligned so both are attracted to corresponding magnets on the sled
      1. TIP: To easily insert the bottom magnet with the correct orientation, attach an extra magnet to the bottom of the sled, then insert the sled into the body and press down.  It will align and press in the magnet for you.
   3. Insert the sled from the top.  It should slide smoothly with no interference.  If your magnets are oriented correctly, you'll feel it stop when the sled is flush with the top of the shell.

Assembly Video walkthrough:

You're done!

BOM / You will need:

• 3  X  M3x6mm screws 
• 5  X  6x3mm magnets
  • Generic magnets (typically N35) work great for the standard height: https://a.co/d/05frdZyH .  For the taller heights when used with long needles I have a small preference for upgrading to stronger N48 magnets: https://a.co/d/06sPYik6 .  I don't like the feel of the stronger magnets on the standard height - but feel free to mix and match for whatever your preference is.
• 2 X 4mm x 50mm stainless pins: https://a.co/d/0aaEQyx8
• 2 short pieces of filament (something slippery - doesn't matter much beyond that it's smooth)

Changelog:

• 3/14/26: Added assembly video guide
• 3/14/26: Added details to BOM on recommended magnet strengths
• 3/19/26: Updated 1ml U100 Syringe adapter with a better fit
• 4/4/26: Added an additional magnet space on the bottom for compatibility with the new  'Vial Drawing Assist'

• 5/12/26: Now recommending 4mm x 50mm stainless steel dowel pins as an alternative to the PTFE rails.  Fits the existing printed parts, slides just as well, but is machined to more consistent tolerances.  Any supplier should work for these but this is the one I tested: https://a.co/d/0hnxdsY9 

  

• 5/20/26: Added adapter for uncommon BD brand 1ml Luer Lock syringes

• 5/25/26: Added a 'seam trench' along interior center of bodies.  Sharp angle encourages slicers to place seams in this channel instead of elsewhere that could throw off tolerances.