Our standard part tolerance is +/- 0.005 in. (0.127mm). If you have a feature that is 0.020 in. (0.5mm) or smaller, our automated quoting system will highlight it as a thin wall geometry, but keep in mind that we'll still allow it to be machined—so the machined part may differ slightly from your original design. Any thin walls that are 0.020 in. or less are not only subject to breakage during the machining operation, but may flex or warp afterwards. Beef them up as much as your part design allows.