How to Measure a Blank and Make a Simple Laser Engraving Jig (Using Cardboard)
This tutorial shows how to measure a blank and create a simple laser engraving jig in LightBurn using cardboard for fast prototyping.
I love making things.
I do not love misaligned things.
Almost centered is not centered. And “close enough” is how you end up redoing work you already did.
So this is Level 1 of my jig series: measure the blank, rebuild the shape in LightBurn or your favorite vector software, and cut a quick jig from cardboard (yes, from an Amazon box).
What you’ll learn in this post
- How to measure your blank and hardware (in mm)
- How to import a straight photo and size it correctly in LightBurn
- How to build a clean jig shape using circles + a connector
- How to add a square frame so the jig is easy to place on the bed
- How to test-fit and adjust if needed
Materials Used
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- Digital Calipers – helpful for accurately measuring blanks and hardware
Recommended digital calipers - Wood Keychain Blanks – the blank used for this jig tutorial
Keychain blanks - Vector software – I used LightBurn
- Cardboard – mine came from an Amazon box
- Laser cutter – any laser that can cut cardboard will work
Step 1: Measure the blank
Measure the wooden disc with calipers. The goal isn’t NASA precision — it’s repeatability. If the measurements are consistent, your jig will be consistent.
Optional: If you want the inch conversion for readers who refuse metric, 39.91 mm is about 1.57 inches. But I’m keeping this tutorial in mm so nobody cries.
Step 2: Measure the hardware
Measure the hardware too. Even if you don’t use it in this first jig version, it matters for later alignment and for future jig upgrades.
For readers who prefer inch measurements, 9.90 mm is about 0.39 inches. I design jigs in millimeters because it makes the measurements easier to work with in most vector software and laser settings, and because I’m Norwegian.
I removed the ring for this version so the blank would lay flat. That ring thickness is a future-me problem (and yes, I’ll cover it later).
Step 3: Take a straight overhead photo (leveled)
Take a straight-down photo of the blank. Use your phone’s level indicator so the photo is actually vertical. Angled photos distort everything.
Step 4: Import into LightBurn and size the photo
Import the photo into LightBurn and use your measurements to size it correctly. The photo is a reference layer — the measurements are the truth.
If you use a different vector program, the process is the same — import the photo, then scale it using your measured circle.
I made a circle at 40mm (even though my blank measured 39.91mm). That tiny bit of tolerance makes it easier to drop the blank in and out without fighting the jig.
Step 5: Build the jig shape (wood + hardware)
Now build the full outline using shapes. Since the hardware measured about 9.91mm, I used an 11mm circle for tolerance.
I like to move the photo off to the side so I can see the geometry clearly. I wanted the two circles to barely touch — that gives a clean transition.
Step 6: Smooth the shape (so it’s easier to drop in/out)
If you keep the circles as-is, the “pinched” area where they touch can make insertion annoying. I add a small rectangle connector and then combine the shapes into one.
Use the boolean operation that combines them into one shape (Union). If you’re like me and never remember which one it is… click until it works. Very professional. 😇
Step 7: Rotate the jig shape
I rotate the jig shape so the hardware is horizontal. This makes alignment easier later when you start placing designs consistently.
Step 8: Add a square frame (so the jig is easy to place)
Now I add a square around the jig pocket. The square is the part you can align to your laser bed / rulers / corners later. Without it, you’re still eyeballing placement.
Step 9: Cut the jig (cardboard is perfect for testing)
I cut this first version from cardboard from an Amazon box. It’s quick, cheap, and perfect for testing size/tolerance before making a permanent jig.
Step 10: Test fit
Drop the blank into the jig pocket. If it fits, you’re done. If it’s too tight, increase the circle size by 0.5 mm and cut again. Cardboard makes iteration painless.
What’s next in the jig series
This jig worked beautifully.
Then I tried aligning it using the laser crosshairs… and learned that crosshairs can be liars.
Next post: how the crosshair alignment messed up my jig placement, and the simple tape method that fixed it.