I've always disliked the stock end caps that come with all Yakima roof rack cross-bars. This design fit the bill of a beefier end-cap while providing a handy loop to hook anything to (bungee cord, rope etc). I was amazed at how strong these are and VERY difficult to get off once you smack them on! They are 5.5cm x 3.5cm x 2.5cm tall (when on the build platform) with nicely rounded edges, especially on the loop so as not to fray any tie-down materials (which made for more complicated polygons and a resulting large-ish .stl file)We'll see how the UV's out here in Colorado treat them, also, it's cold here now, so we'll also see if there's any change in fit once summer rolls around - but it's always easy enough to print more if I have to!As with anything, use at your own risk, but I've had great luck with them so far.I created this using Rhino and printed them one at a time on a heated acrylic platform using ABS (about 50 minutes each) and the latest versions of Skeinfox/Skeinforge updated with the settings found at http://wiki.makerbot.com/configuring-skeinforgeI've been building this 'raftless', but am having trouble doing so on my new kapton covered ceramic platform - the 'loop' wants to pop up which it never did on the acrylic platform - and I hate peeling rafts off the bottom of builds. Strength was a main concern here, so I wanted the fills pretty solid.I can fit three of these at once on the build platform and will be trying that soon. I just got my new ceramic heated platform working and will try one on there.I now have some colored ABS and may try some in colors, but feel as though it may draw too much attention = theft :-)I recently designed an even bigger/ beefier version (7cm x 4.5cm x 2.5cm) and will post those soon. They're kind of ridiculously large, but kinda cool.