Print-in-Place Articulated Models: How a Flexi T-Rex Moves Without a Single Screw
Imagine pulling a dinosaur off your print bed and its jaw already snaps open, its tail already swishes, and its little arms already wave, all without glue, screws, or a single support to clip away. That is the magic of a print-in-place articulated model, and a new Flexi T-Rex doing the rounds on MakerWorld shows it off perfectly.
Print-in-place means the moving joints are printed already assembled. Your slicer lays down a microscopic gap, usually around 0.2 to 0.3 mm, between two parts so they sit inside one object but never actually touch. When the print finishes you flex the joint once to break it free, and suddenly you have a hinge, a ball socket, or a chain link that swings on its own. Nothing to assemble.
The reason these prints feel like wizardry is that they lean on the one thing FDM printers do best: stacking thin layers with fine precision. Because the gap is baked into the 3D file itself, the printer never knows it is making moving parts. It just follows the path. That is also why articulated prints make such a satisfying first project: the design does the hard work, and you get a fidget-worthy toy straight off the plate.
Getting a clean result comes down to a few habits. Print the first articulated model slowly so the layers bond. Keep your bed level and your first layer dialed in, because a squished base can weld the joints shut. Skip supports, since good articulated designs like this plug-together T-Rex (the body, head, and jaw print separately) are made to avoid them. And once the part cools, gently wiggle each joint to free it rather than yanking on it.
Want to try it on your printer? Articulated flexis are the perfect weekend print, and they are exactly the kind of approachable, fun project we love at Flarelab. Load up a print-in-place model, drop your layer height to around 0.16 mm for crisper joints, and watch a flat plate of plastic walk off the bed as a living, moving creature.
Frequently asked questions
What does "print-in-place" mean?
It means the moving parts are printed already assembled. The 3D file includes a tiny built-in gap between parts, so the joints come off the bed working with no glue or assembly.
Do articulated models need supports?
Well-designed ones do not. They are modeled to print support-free, and adding supports can actually jam the joints. The Flexi T-Rex prints its body, head, and jaw separately with no supports at all.
What layer height works best for articulated prints?
A finer layer height of around 0.12 to 0.20 mm gives smoother, freer-moving joints. A 0.20 mm setting prints faster and still works well for a first attempt.
Why will my joints not move after printing?
Usually an over-squished first layer or too much extrusion fused the gap shut. Re-level your bed, check your flow rate, and gently flex each joint once the print has fully cooled.
Inspired by a community build shared via Adafruit's #3DThursday (Flexi T-Rex by Remb Studios on MakerWorld). Written and published by Flarelab. Flick the Fox artwork by Flarelab.