FractMod (KMT)- Keyhole Marking Tool

***UPDATE NOTES AT BOTTTOM***

 

Never guess a keyhole location again.

 

This compact marking tool makes mounting shelves, wall décor, and hardware fast, clean, and accurate. Simply slide the spring-loaded plunger into the keyhole slot, tighten the locking nut, position and level the piece on the wall, press against the surface, and the built-in marker leaves a precise drilling point every time.

 

Features

• Spring-loaded plunger for easy, repeatable keyhole alignment without accidental marks on the wall
• 100% printed design- no extra hardware required
• Precision contact tip leaves a clean, accurate drill mark
• Small, handheld, and shop-ready- print 2–3 to mark multiple keyholes at once
• Durability tested- 4 springs were printed in PLA and survived 500+ full cycles with zero failures

This tool completely removes the guesswork from mounting anything that uses keyhole-style hardware.

 

 

Print Recommendations

• Material: PLA or PETG
• Layers: Use adaptive layer height to preserve accurate features on the spring, threads and plunger
• Infill: 10–15%
• Orientation: Print the spring vertically (axially)
• Supports: Tree support touching build plate only (for the top flat of the spring)

Print profiles have been optimized to provide a clean, repeatable, and accurate print on most machines.

 

 

Assembly Instructions

• Remove all parts from the build plate
• Remove supports from spring (supports should easy break off), clean up any stringing on the inside and outside of the spring
• Slide the spring into the body, a slight twisting motion may be needed.
• Place the plunger on top of the spring with the latch at the bottom.
• Place the assembly tool in top of the plunger and body. Flip upside down and using a hammer, tap the plunger into the body.
• Thread on the locking nut
• Thread the alignment screw into the base of the body.

 

 

Looking for a way to protect and store your KMT?

Check out the print in place case that is out now!

 

 

Need to hang something with two Nails?

Check out my new two-nail marking tool! Great for frames up to 24" wide using the same great fully 3D printed design.

 

Boost MeIf you enjoy functional shop tools like this (jigs, measuring devices, print-in-place mechanisms, precision fixtures, etc.), please consider Boosting this project.

Boosts help increase visibility and directly support future tool development.

 

Thank You & Community Feedback

 

Thank you for checking out this design! Your feedback directly shapes future improvements, so please:

🔧 Post a make if you print it

📝 Leave feedback about print quality and performance

💡 Suggest features you’d like to see in future versions

 

Your input helps refine these tools and expand what’s possible with functional 3D printing.

 

11/30/2025- 2nd Print Profile- FractMod- Keyhole Marking Tool (BRIM)

Print Profile was added to include a brim at the bottom of the spring, due to reported print issues. This brim was optimized to be easily removed after the print is completed with minimal cleanup needed. 

 

The original profile remains if you wish to print without a brim but the new profile is recommended for the A1 and A1 Mini.