From part to print

The part is checked and exported; here is how to get it from parts/<name>/out/ onto the printer with Bambu Studio, OrcaSlicer or PrusaSlicer (Cura works the same way). Over a remote server, bring the part home first (download_part, or b123d-print pull).

Which file

File	Use it when	Why
<name>.3mf	almost always	carries millimeters, so it can't be scaled wrong; standard 3MF that Bambu Studio, OrcaSlicer, PrusaSlicer and Cura all open
<name>.stl	a slicer or service that wants STL	no units: slicers assume millimeters, which is right for these files; a mesh, a little larger
<name>.step	you want to edit the part in other CAD	an exact solid without history. Slicers that import STEP turn it into a mesh themselves; use the 3MF instead, which b123d-print meshes finely
<name>_print.md	always worth a look	the print sheet: what the part assumes, in one page

Pick the formats with formats= on export (or formats in your config): 3mf,print is a good default for printing at home. See Output formats.

Bambu Studio: \"The 3mf file has invalid config, load geometry data only\"

Expected. The 3MF has the shape in millimeters but no Bambu project settings (printer, filament, plate). Click OK and slice it with your own settings (more, troubleshooting).

Orientation: as exported

Every piece is exported in print orientation, with its bed face on Z = 0: the part script's build(d) returns it that way, and the checks ran on it that way (overhangs, bridges, bed edges, tip-over). So:

• Don't re-orient it. Skip Auto Orient, and don't lay it on another face (OrcaSlicer's "Lay on Face", PrusaSlicer's "Place on face", F): the overhang and strength choices were made for this side down. If you think another side is better, ask the assistant to run suggest_orientation and change build(d), so the checks follow.
• Move it freely in X and Y. If a piece lands off the plate, use Arrange (A).
• Strength: layers are the weak direction. For a part that carries load (the structural style), the main load should run along the layers; that is why a bracket may lie on its side. Turning it in the slicer undoes that.

Settings the part assumes

Most parts print with your usual profile. What to check:

• Material. The fits (clearance, press_fit, free_fit) and hole compensation are tuned for your printer and material (Settings, calibration). Printing in another material changes them: PETG fits a little tighter than PLA, and ABS, ASA and nylon shrink and warp (brim, enclosure, BP-B3/B4).
• Walls before infill. Strength comes from the walls (perimeters). The slicer default (2-3 walls, 15 % infill) is fine for most parts. For the structural style use 4-6 walls and 15-30 % gyroid infill, and 3-4 or more walls around screw holes and bosses (design guide). The setting is Wall loops in OrcaSlicer (Bambu Studio, which OrcaSlicer comes from, uses the same idea), Perimeters in PrusaSlicer and Wall Line Count in Cura; infill is Sparse infill density (OrcaSlicer), Fill density (PrusaSlicer). For a few bosses only, use a modifier instead of more walls everywhere: PrusaSlicer right-click → Add modifier or Height range modifier; OrcaSlicer and Bambu Studio have the same right-click modifiers.
• Hole compensation: once, not twice. b123d-print adds your hole_comp to the holes in the CAD. Leave the slicer's own hole correction off (OrcaSlicer: X-Y hole compensation on the Precision page, Cura: Hole Horizontal Expansion); PrusaSlicer has only a general XY Size Compensation, which also shrinks or grows the outside: leave it at 0.
• Elephant's foot. Keep the slicer's Elephant foot compensation on (OrcaSlicer: Precision; PrusaSlicer: Print settings → Advanced). The CAD stays at nominal size; the bed edges get a chamfer rather than a fillet so they print cleanly.
• Supports. check (the overhang check) and suggest_orientation say what needs support. Most parts here need none: turn supports off, or set them to On build plate only (OrcaSlicer) / Supports on build plate only (PrusaSlicer), so nothing grows inside holes and pockets. Where the report or print sheet names supported faces, enable supports; those faces come out rough.
• Brim. The tip-over check warns about tall parts on a small footprint: use a brim of 5-10 mm or mouse ears (OrcaSlicer: Brim type Auto or Mouse Ears).

Several pieces

A part with several pieces exports one file per piece (<name>_base.3mf, <name>_lid.3mf), each in its own print orientation.

• Open them together (select all the files, or import one after another) and use Arrange. If the slicer asks whether to load them as one object with several parts, answer no: they are separate objects, each with its own bed face.
• Print them together or apart. Together saves time; apart lets each use its own settings (a lid with fewer walls, a bracket with more).
• Fit-test templates (<name>_template_*.3mf) are separate quick prints: print one first when the fit matters (templates).
• Assembly: the order, glue and inserts are in the assistant's report and, if the script sets PRINT_NOTES, in the print sheet. For split parts see Splitting parts.

The print sheet

export with the print format writes out/<name>[_<variant>]_print.md, one per variant: the report you'd otherwise scroll back for, next to the files, and download_part brings it home with them. It is off by default; ask for it with formats="3mf,print", --formats 3mf,print, or formats = ["3mf", "png", "print"] in your config (all includes it). It costs about a second per piece.

It lists, from the part as built:

• per piece: size, volume, filament (simple estimate, roughly ±20 %) and print time (rough);
• the orientation, the faces that need supports (and small overhangs right at the bed), bridges longer than max_bridge, tip-over risk with brim advice, and holes lying on their side;
• the material and printer it was designed for, walls and infill for its style, screw holes that want more walls, the script's Wall checks, the fits and hole compensation applied (and the reminder to leave the slicer's hole compensation off);
• the pieces and PRINT_NOTES (a string or list in Dims, see the part script).

It uses the cheap estimates from design_metrics and the tip-over check, not the full check run: run check for the verdict. The numbers are the same rough estimates; the slicer's are the real ones.

If the script defines hardware(d), the sheet includes a Declared hardware table: exact specifications and quantities supplied by the author for the whole selected variant assembly, even when parts= / --only exports one piece. Hole-based screw classes remain inferred advice, not a shopping list. An empty specification says Needs confirmation; never guess a screw length, thread, head or insert model from a hole or imported mesh.

Add hardware to the formats (formats="3mf,print,hardware") for the matching <name>[_<variant>]_hardware.json. Both artifacts go home through the existing export links, download_part and SSH pull (include both print,hardware when filtering formats). See declared hardware for the hook, custom imported stand-ins and JSON format. A script with no hook keeps its existing print sheet.