Clearances before you begin

No. Many builds work in plywood, brass tube and off-the-shelf hardware. A printer speeds up iteration, but the failure-mode notes apply to any material. See Compact Motion.

Rated pull is measured perpendicular to a thick steel plate with zero gap. Gaps, thin steel, coatings and sideways loading all reduce real holding force sharply. Details in Magnetic Builds.

For machined metal, use ISO 286 classes such as H7/g6. For printed parts, print a test coupon on your own machine and measure what slides freely. See Precision Machines.

Size and gap matter as much as grade. N35 to N42 is fine for most builds; choose higher-temperature grades if the part sits near heat above about 80 °C.

Put metal at the wear points: steel or brass pins, purchased bearings and bushings. Make the wearing part cheap and replaceable.

Loose small magnets are a serious swallowing hazard. Fully enclose magnets in finished builds and keep loose magnets away from children and pets. Keep strong magnets away from pacemakers.

Backlash is the play when a drive reverses direction. Anti-backlash nuts, preloaded gears and approaching targets from one direction reduce its effect; eliminating it entirely usually costs friction.

Gridfinity was released by Zack Freedman as an open-source system and many community designs are shared freely. Check each design's own licence before selling prints. More in Smart Storage.

They usually display 0.01 mm but are commonly specified to roughly ±0.02–0.03 mm. Use a micrometer or gauge pins for critical fits.