A print-in-place sliding puzzle comes off the build plate as one finished object — no assembly, no fasteners, no glue. Nudge a tile and it moves. Miss the clearance by a tenth of a millimetre, though, and you either pull a solid brick off the bed or a tray of loose, rattling squares. A recent Maker's Muse build of a parametric sliding puzzle, later decorated with a desktop UV ink printer, is a good reminder of how narrow that window really is.
The whole design lives or dies on clearance: the air gap you deliberately model between two surfaces that need to slide past each other. An FDM printer does not deposit plastic exactly where the slicer draws it. Extrusion width wanders, corners bulge a little, and squished first layers spread outward. So a modelled gap of zero prints as a weld. Go too far the other way and the tiles tip in their slots, the frame flexes, and a piece eventually pops clean out of the tray.
Geometry carries as much weight as the number does. Sliding faces need shapes a printer can actually reproduce — flat vertical walls, small chamfered lead-ins, and no unsupported overhangs much past 45°. Scale compounds everything: a 3×3 grid forgives sloppy work, while an 11×11 grid stacks eleven tolerances in a single row, so a gap that felt perfect on a small test turns into visible slop across a large one.
To dial it in, print one small test tile before you commit to the full grid. Start around 0.20 mm of clearance per side on a tuned machine, then run 0.15 mm and 0.25 mm variants and compare how they feel in the hand. Set your slicer's horizontal expansion or hole-compensation value deliberately instead of trusting the default, slow the perimeters on the mating walls, and keep layer height modest so the vertical faces stay square. If every variant binds, your extrusion multiplier is almost certainly too high — fix flow calibration first, because no clearance value rescues an over-extruding printer.
Try it on your printer. Print a 3×3 grid in something stiff like PLA or PETG, and write down the clearance that felt right. That single number carries over to every print-in-place project you make afterwards: hinges, living-hinge boxes, articulated figures, snap-fit lids. Browse filament and printer gear at Flarelab, then come tell us what number your machine settled on.
Frequently asked questions
What clearance should I use for a print-in-place sliding puzzle?
About 0.20 mm per side is a reliable starting point on a well-tuned FDM printer. Print one test tile at 0.15 mm, 0.20 mm and 0.25 mm and keep whichever slides freely without rattling in the tray.
Which filament works best for print-in-place puzzles?
PLA and PETG both work well. PLA is stiffer and holds tolerances more predictably, which makes it the safer first attempt. PETG is tougher but strings more easily, and stray strands in the gaps will jam the tiles, so keep retraction tuned.
Why did my puzzle fuse into one solid block?
Almost always over-extrusion or a model with no clearance built in at all. Run a flow calibration and check your extrusion multiplier before you start widening gaps, otherwise you will just chase the problem into a looser, still-fused print.
Can I add full colour to a finished puzzle?
Yes. A desktop UV ink printer can lay a colour image, or even a textured relief, straight onto a flat puzzle face. The catch is that ink landing in the seams gums up the sliding action, so mask the gaps or design the artwork to avoid them.
Originally published at flarelab.com.
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