STL Merge, Split & Cut Tool
Merge STLs onto one plate, split shells apart, or cut a model with a plane.
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See STL Merge, Split & Cut Tool in action
Free STL Merge, Split & Cut Tool
Print plates are often built from several files. The Merge tab loads two or more models and arranges them in a grid, a row, a vertical stack, or keeps their original positions (for assemblies), with a spacing you choose and an option to drop every part to the bed. Each part is colour-coded in the preview, and the result is one mesh you can download as STL, 3MF or OBJ.
The Split tab does the reverse: it finds every connected shell in a single file — useful for multi-part downloads and sliced-plate exports — and lists each one with its size and volume so you can download parts individually or as a ZIP. The Cut tab slices a model with a plane along X, Y or Z, adds flat caps so both halves are watertight, and lets you download each half — ideal for printing tall or oversized models in two pieces.
Use it in 4 steps
Choose Merge, Split or Cut.
Drop in your file(s).
Adjust arrangement, pick shells, or move the cut slider.
Download the result.
Key features
Merge with auto-arrange
Grid, row, stack or keep positions, with colour-coded preview.
Split into shells
Every disconnected part listed with size and volume, downloadable alone or as ZIP.
Capped plane cut
Cut along X/Y/Z with a slider; both halves are closed solids.
Any format
STL, OBJ, 3MF, PLY, STEP in; STL, 3MF, OBJ, PLY out.
A real example, step by step
Four STL parts dropped into Merge → arranged on a 2×2 grid with 5 mm gaps and dropped to Z = 0 as one STL. A 120 mm tall figure cut at Z = 60 gives two watertight halves that each print flat.
Who uses this tool
Makers building a multi-part plate
Combine files without opening a slicer.
People with a 'plate' STL
Extract single parts from a combined file.
Printing tall models on small beds
Cut, print flat, and glue.
Tips for the best results
- Cut with the section view first, so you see where the plane falls.
- For a clean glue joint, cut at a flat area and consider adding pegs in CAD.
- Parts that overlap in 'keep positions' mode are not boolean-unioned — slicers handle overlaps as a union anyway.
- Run the repair tool first if a cut says a half is not watertight.
Common mistakes to avoid
- Cutting a non-watertight mesh and expecting closed halves.
- Merging parts at identical coordinates so they overlap.
- Forgetting the gap so parts touch and fuse in the print.
Frequently asked questions
Does merging boolean-union overlapping parts?
No — it concatenates the meshes. Slicers print overlapping closed shells as one solid.
How does splitting detect parts?
By connectivity: triangles that share vertices belong to the same shell.
Can I cut at an angle?
Cuts are along X, Y or Z. Rotate the model first with the transform tool for an angled cut.
Is it private?
Yes — nothing is uploaded.
Free, fast and private by design
No signup, no watermark. New AZRS tools are added every week.
