Split a model for your printer, unfold it to foam, and attach it to a build

Cut a scaled model into parts that fit your print bed with pin holes to line them up, or unfold it into flat foam templates, and log the fit against a piece in My Builds.

CosplayersUpdated October 11, 2026

~7 min
Comfortable
Part 3 of 3

A full helmet rarely fits a print bed in one piece, and some makers would rather build it in foam. Fit Forge does both from the scaled model.

Before you start

A model previewed scaled (see part 1).
To attach it: a build with pieces in My Builds.

Split it for your printer

Pick your printer
Under Split for your printer, choose it under Printer. Not listed? Choose Another printer… and type its Width, Depth and Height in mm.
Choose how the parts join
Join with: 1.75 mm filament as pins (the default), Printed 4 mm pins, 6 mm wooden dowels, or No pins — I'll glue it.
Split
Press Split into parts.

Check it worked

It reads … parts for …, joined by … pins — … mm long, … mm holes. (or It fits … whole — no cuts needed.), with each part's size. Every cut is closed, and matching holes are drilled where the wall is thick enough.

Download parts (.zip) gives one STL per part, a note of how they go together, and — with printed pins — the pin to print. Download parts (.3mf) holds every part where it sits in the whole model; use your slicer's Arrange to lay them out.

Or unfold it to foam

Set it up
Under Unfold to foam templates, keep The outside only ticked — foam only needs the outside. Choose a Detail (Balanced to start).
Set the curve
How curved one piece may be, 15° to 60°: lower makes more, flatter pieces; higher, fewer pieces that bend more.
Unfold
Press Unfold. It reads … pieces from … facets, with … of seams to glue.
Print or cut
Open print sheets prints them at true scale. For a cutting machine or laser, choose the Material width and press Download cut SVG or Download DXF; Project onto your mat projects them instead.

Printing, checking and cutting templates is the same in every tool — see Print and cut foam templates.

Attach the fit to a build

Pick the piece
Under Attach to a build component (optional), choose the build and piece (Build — piece). No piece yet? + New piece on a build adds one; pick the build, name it, and press Add piece.
Download
Download the scaled STL or 3MF as usual.

Check it worked

It reads Downloaded. On the build, the piece's in the workshop line says Fitted once, last …. Starting from Fit › on a build picks the piece for you.

Live BOM, on Plus and Pro

With Plus or Pro, the Live BOM prices the piece in the material you choose, and downloading with a piece attached sets that piece's estimate to the BOM figure — Downloaded — estimate saved to your build component. On Free, everything else here works the same.

If something's off

“Couldn't split this model…” / “Couldn't unfold this model…”: The model has holes or loose pieces. Run it through your slicer's repair tool first.
“… too thin for a pin there — glue it instead…”: Some cut faces can't take a hole. Glue those joints, or pick a thinner pin.
I can't see Split for your printer: It appears after Preview scaled.
“Your browser blocked the print window…”: Allow pop-ups for this site, or download the SVG and print it at 100%.

Still stuck? Browse all help or contact us. To report someone or something, use the report action on the relevant profile, post, or session — it sends us the context automatically.