3D Miter Cuts With FitUp Assembly Builder

Every fabrication project starts with an idea, but turning that idea into an accurate, weldable assembly is where the real challenge begins.

For this project, I designed an infinity-shaped tube sculpture using FitUp, the 3D tube layout tool built into FabToolkit. While the finished piece looks simple, it contains several compound miter joints that would be difficult to measure and cut by hand.

The infinity sculpture design laid out in FitUp Assembly Builder's 3D view, showing the tube runs and compound miter joints.

Designing in FitUp

After laying out the assembly in 3D, FitUp automatically generated a complete build packet, including cut lengths and printable tube templates. Instead of spending time calculating angles or making trial cuts, I could move directly to the shop with everything I needed.

The FitUp build packet showing the cut list with lengths, quantities, and material specs for each piece of the infinity sculpture.

From the Printer to the Shop

The fabrication process included:

Cutting each tube to length
Wrapping the printed templates around the tubing to mark the miter cuts
Trimming the pieces
Checking the fit
Welding the entire assembly together

Printed miter templates and cut tube pieces laid out on the workbench alongside the build packet drawings.

Hands tracing the miter cut line from a printed template wrapped around a tube, with the assembly drawing visible in the background.

The cut tube pieces assembled and taped together in a test fit, confirming tight joint contact before welding. The FitUp build packet is visible in the background.

The Finished Piece

The result matched the digital model closely, demonstrating how accurate planning can simplify even complex tube projects.

The finished welded infinity tube sculpture, polished and displayed on a marble surface.

Making Complex Joints Accessible

One of the goals of FitUp is to make projects like this accessible without requiring expensive CAD software or a steep learning curve. Whether you're building handrails, roll cages, furniture, sculptures, or custom fabrication projects, the workflow stays the same: design the assembly, generate the build packet, and head to the shop with confidence.

If you've ever spent hours trying to figure out compound tube joints, this project shows how much time can be saved by planning the build before making the first cut.

Try FitUp Assembly Builder

Lay out your frame in 3D. Get every miter angle, cope template, and cut list — automatically.