Most failed prints are not slicer problems. The lid is too tight, the hole too small, the text too thin, the round edge on the bed droops. Lets3dPrint is CAD that knows these tricks and does them in the design, so the part is right before it reaches the slicer.
macOS 26 or later · Apple silicon · Modelling and the parts library are free; export, Print Check, textures and scripts with Pro
It goes together
A printed hole comes out smaller than you drew it, and two printed parts need a gap to slide. Here the gap is part of the tool, so you set it once instead of guessing on every part.
Click a round face, pick the size. Metric threads from M2 to M30, outside on a rod or inside a hole, with extra room for printing (0.2 mm to start, yours to change).
Split a part along a sketch and the pieces get jigsaw or dovetail locks with the clearance cut in (Tight, Normal, Loose). Or split it with a plane and join it again with a lock you push in and turn.
The Fit test in the library prints five holes, each a step looser, and pegs to try in them. The loosest snug fit is your printer's clearance.
A sideways hole sags at the top. Pick Teardrop or Flat roof and it prints without support.
A counterbore that opens downwards gets a one-layer bridge, so the printer has something to lay the screw seat on.
It prints
Thin walls, overhangs, a part off the bed, the first layer squeezing out: usually you find them in the layer preview and go back to CAD. Here they show up while you design, on the part itself.
Set the nozzle and layer height. Walls too thin to print, walls only one line thick, gaps that will close or fuse: marked on the model, worst first, with a button that turns the view to each one.
Pick your printer (Bambu Lab, Prusa, Creality, Elegoo) and its bed sits under the model, red where a part sticks out. Lay a part on the face you click, arrange everything on the bed.
Faces that lean out past 45° (or your own angle) turn red, so you see where support would go.
One click chamfers every edge that touches the bed (0.4 mm), against the first layer's squeeze-out.
Brim Ears puts thin discs on sharp corners at the bed, so they do not lift. You snap them off after printing.
Measure gives volume, filament weight and length for PLA, PETG and other materials.
Draw the cut lines and Joint Split makes the pieces with locks. Every piece is its own body, ready to export.
3MF with every body as its own named, coloured object; STL for any printer; STEP for Bambu Studio, PrusaSlicer and OrcaSlicer.
Downloaded models
Most things on Printables and MakerWorld are meshes. Bring one in and it becomes a solid you can work on, with its flat faces as real faces, on your Mac, without an online converter.
Click a flat face of the imported part and click where the holes go: simple, counterbore or countersink, through or to a depth.
Text and SVG logos raised or sunk into a face, flat or curved, at the depth you type.
Extrude a flat face, sketch on it, cut a slot, join a bracket, split it with a plane. STEP models open with every part a body, with names and colours.
Functional prints
Boxes, bins, jars, enclosures, hooks: the things generators on the model sites make. Here they arrive as ordinary steps in your timeline, so you can still fillet, cut and label them.
Stackable box, drawer tray, Gridfinity-compatible bin and baseplate, screw-top jar, board enclosure, spur gear, knob, wall hook, cable comb, plant pot, name tag and the fit test. Set the sizes, press OK.
Every project is also a short script. Put a few numbers at the top and they become sliders: six cable slots or ten, one drag. Save it and use it again in any project.
Easy to start
You do not have to define a sketch fully before you can use it. Draw rectangles and lines, type the sizes as you go, and change any step later.
Width, height, distance and angle boxes sit next to the cursor and the arrows. Type a number or a sum like 40/2+3.
Every tool works the same way: click what it works on, see the result, drag or type, then OK or Cancel. Nothing changes before OK.
Make an early sketch bigger and the whole part rebuilds, holes and fillets included. Suppress or roll back any step.
Press ⌘K and type what you want: "hollow", "screw", "warp". The tool starts.
No account, no cloud, no limit on projects. They are files in Finder and iCloud Drive.
Modelling is free. Pro is $0.99 a month or $6.99 a year, with a free first week.
One fit list for every hole, thread and joint, your printer's offset from the Fit test, holes sized for heat-set inserts, nuts and magnets, inlays for a second filament, and more. See what comes in 1.7 →
Download Lets3dPrint and model as much as you like for free. Go Pro when it is time to print.
Download freemacOS 26 or later · Apple silicon