Fidget Spinner / Simplicity Wins U225X / MDL-SPINNER-001 / 2026.09.15 I wanted something that would spin freely and keep going after a flick. That small goal led through Shapr3D extrusion controls, smooth connecting arcs, bearings that felt stiff, and a question about putting N52 magnets around a printed housing. The result on the workbench is a white, three-lobed spinner with four bearings. The useful part of the project was working through those questions and coming back to a simple object I could actually make. BUILD STORY The theme for this build is simplicity wins. A small printed mechanism gave me a reason to learn a few CAD controls, question the bearing resistance, and follow a tempting magnetic idea far enough to understand its limits. First, make the material join. In Shapr3D I wanted to extrude a circle downward to create a connection, but the operation was subtracting material. The useful control was the Boolean badge beside the extrusion distance: choose Union when the intent is to add the extrusion to the existing body. It was a small interface detail with a large effect on what the model became. Then make the circles feel like one shape. The sketch had a central ring and three rings around it. I marked the connections I wanted in red: inward curves between the outer circles. The advice was to start with a 3-Point Arc, keep each endpoint coincident with its circle, and make the arc tangent to both circles. Coincident keeps the endpoint attached; tangent makes the transition smooth. The endpoints need room to slide while those constraints solve. Those notes explain the approach discussed, while the screenshot preserves the shape I was aiming for. The bearings raised another question. The new bearings felt a little stiff, so I asked whether WD-40 would help. The discussion redirected attention to the source of the drag: grease, seals, an overly tight printed pocket, or a surface rubbing after assembly. A useful check is to compare the bearing before and after fitting it. The conversation did not establish that I changed the lubricant or measure how much resistance came from the housing. Then came the magnetic detour. What if N52 magnets sat in pockets around a PLA bearing housing? I wanted the spin to last longer, and magnets snapping together or pushing apart made it feel as though there ought to be something useful there. The discussion separated a magnetic push from a continuing source of energy: a fixed arrangement may help during one part of the rotation and resist during another. Resetting an attracting or repelling arrangement takes energy. Simply arranging magnets around a bearing does not supply a new push on every revolution. There was still an interesting experiment to keep. Magnets can support some of a rotor's load in a suitable arrangement, reducing what the bearing has to carry. That is different from expecting a steel bearing to repel a magnet, or expecting magnets fixed inside one housing to drive that same housing around. A removable magnet setup and repeated comparisons were suggested. No such comparison is documented here, so the magnetic idea remains a question for another test. Back on the workbench, the result is straightforward: a white printed body, three rounded lobes, and four bearings. The photo gives the CAD discussion a physical ending. The STL keeps the shape available for the next attempt. Simplicity wins here because the project has reached an object I can hold and examine; the more elaborate ideas can wait until there is a useful measurement to compare them against. MODEL AND BUILD NOTES Build tag: Simplicity wins Layout: One central bearing position / three outer lobes Outer spacing: 120° / bore centers 26 model units from the center Model envelope: 70.03 × 64.00 × 4.98 model units Bores in STL: Four / approximately Ø12.62 model units Units: STL is unitless; these values are millimeters only if imported as mm Material record: PLA discussed for the housing; final filament and print settings not recorded Bearing identity: Four installed in the photograph / exact specification not recorded Original file: Binary STL / 226,746 triangles / 11,337,384 bytes Before printing: Check scale and slicer repair/preview; original mesh contains internal nonmanifold faces Performance: No measured spin time or magnets-on/magnets-off comparison recorded FILE INTEGRITY Original STL is unchanged. SHA-256: f90ee8d1634c26e9206dba10825ea6f93fd20207beab8d8c0a2ef14eb502b4bf MESH CHECK The STL is one vertex-connected assembly. It contains internal/nonmanifold geometry, chiefly near the midplane; 1,552 edges have four incident faces. No open boundary edges were found, but this is not a verified watertight mesh. Inspect slicer repair and layer preview before printing. Bore sizes are mesh measurements, not a guaranteed bearing fit. IMAGE PREPARATION The supplied photograph was oriented upright, resized, and stripped of metadata for the web. Its full composition is retained. The Shapr3D screenshot is preserved as supplied. SOURCES Extrude Circle Union: https://chatgpt.com/share/6aa9e9c7-faf8-83ea-9e1e-c72ad0d1ef23 Magnetized Ball Bearing Effects: https://chatgpt.com/share/6aa9e9a9-9e5c-83e9-8969-186f9df6cf65 Shapr3D Extrude: https://support.shapr3d.com/hc/en-us/articles/7874453786908-Extrude Shapr3D Tangent: https://support.shapr3d.com/hc/en-us/articles/9307945448860-Tangent Connecting arcs: the accompanying Shapr3D discussion and supplied screenshot in this build task, September 15, 2026. EVIDENCE The shared chats contain questions and proposed guidance, not a measured test log. The photograph documents the assembled object. Printer settings, final filament, bearing part number, spin duration, and a magnets-on/magnets-off result were not supplied.