Ruliper — Metric + Inches

Flat Sliding Ruler & Caliper — Metric + Inches

I designed this flat ruler with a captive sliding jaw for measuring outside dimensions. Read millimetres or inches at the red index, or use the outside edges as a regular ruler. Five printed parts snap together without purchased hardware.

I printed and assembled this initial release and tested the sliding action. The lettering and scale marks print face-down against a smooth sheet for a clean, readable finish.

Features

- Metric and inch scales: 0–230 mm and 0–9 inches. - Outside caliper range: 0–205 mm, approximately 8.07 inches. - Ticks on both sides of each scale: use the outer rows as a ruler and the inner rows beside the slide for caliper readings. - Clear inch hierarchy: whole, half, quarter, eighth and sixteenth inches. - Readable centimetre labels: 0–9, then 10, 12, 14, 16, 18, 20 and 22. Every millimetre tick remains, including the final 230 mm tick. - Flat top and bottom: no raised feet; the index and lettering are flush. - Captive slider: a small printed key limits travel, while the guide shoulders control movement. Closed dimensions are 269 × 42 × 8 mm . Graduation spacing is 1 mm and 1/16 inch; it is not a claim of calibrated measurement accuracy.

Printing

I prepared the included Bambu Studio project for an X1 Carbon, 0.4 mm nozzle, AMS, Bambu PLA Basic and a smooth build plate . Use the supplied arrangement:

Plate Parts Colors

1 Two frame halves Black body / white scales

2 Two slider halves and the captive key Black body / red index

0.20 mm layers, 3 walls, 100% infill, no supports. All three filament slots use the built-in Bambu PLA Basic preset; match the slots to your AMS spools. Keep the marked faces on the plate and retain the supplied orientations.

Slicer estimate for both plates: 4 h 26 min, approximately 109 g PLA and 10 filament changes . These figures include the slicer's purge/tower estimate. The two-plate arrangement retains 10 mm plate-edge margins. I have not tested other printers, filaments or plate finishes.

Assembly

- Identify the two frame halves, two slider halves and small T-shaped key. The upper frame carries both scales; the upper slider carries the red index. - Place the lower slider with its socket facing up. Fit the key's narrow neck into the socket near the rounded end. Its broad head points toward the metric scale. Snap the upper slider onto the lower slider, trapping the key. - Place the lower frame with its channels facing up. Seat the assembled slider between the guide arms, with the key head inside the metric-side stop channel. - Align and press the upper frame onto its pins evenly. Seat the seam fully along the length. The design is intended for dry assembly; keep glue out of the guides and key channel. - Close the jaw and check that the index reads zero on both scales. Move through the full travel and confirm the key stops the slider from escaping. The illustrated assembly PDF includes a close-up of the key orientation.

Reading and adjusting

Read the red line against the scale nearest it. The lower numeric labels are centimetres: for example, the third millimetre tick after “2” is 23 mm . The upper scale is in inches, with the shortest ticks at 1/16 inch .

Check a known dimension before relying on a measurement. If the slider binds, first check for an incompletely seated seam or loose print debris. Do not scale the entire model in the slicer: that changes the scale spacing and the fit. I included five complete STL pieces: upper and lower frame, upper and lower slider, and the captive key. Each STL is a single solid in its printing orientation; no separate inlay meshes need alignment. These are single-color alternatives with the flush inlay regions filled. For readable contrasting scales and the red index, use my Bambu Studio print profile , which already groups the colors into five pieces and arranges them across two plates.

Inspiration and license

I took inspiration from the Craighill Metrolog ruler . Vostok Labs' Ruliper gave me a useful benchmark for readable printed markings. I built the CAD independently, and I am not affiliated with either creator.

I am sharing this design under Creative Commons Attribution–NonCommercial 4.0 . Noncommercial sharing and remixes are welcome with credit, a license link and an indication of changes.