After a tip by Ruff, I decided to test graphite impregnated bronze bushings to replace LM8UU linear bearings, as a way to decrease the noise from my P3Steel and Prusa i3 printers when printing. I made a video comparing the noise of these graphite impregnated bronze bushings to that of a low cost LM8UU bearing: https://www.youtube.com/watch?v=AbSU_rI82-4 These printed adapters have customizable tolerances which can be adjusted to your specific printer to get a perfect fit of the bushings. The default values are the ones I arrived at after a few tries. Based on http://www.thingiverse.com/thing:849572 by Ruff, and also on http://www.thingiverse.com/thing:166794 by Misan. OpenSCAD sources are included so the thing can be further remixed. Released under the GPLV3 license. Here printed in PLA with 35% infill. Requires two bushing per adapter. These graphite impregnated bronze bushing are available from AliExpress for less than $0.35 each, in packs of 10. I put them in the fridge for about an hour before press-fitting them in the still warm adapter.