Have 3D printed a useful item the other day. A friend is adding new fans to his PC and asked if I could print of fan mount. He found this > here over at Thingiverse.com. Gave it a try and it turned out great. This is the first time I had printed anything that had 100% infill. Figured it would take really long. But only three hours. Could have printed it faster but I like to keep the quality.