I know it's probably not likely to happen until more official modding tools are available, but I'd like the walls (and prefab corner walls), fences, carpets, flooring, roofing etc to be able to precisely self-connect edge to edge on four angles at the corners, instead of only one way. It was pretty irritating when I found out that wall pieces and corners only snapped in place in one direction. That is pretty much a travesty, and made it a nightmare to get anything to look right. You really should be able to have wall panels stick together backwards or at right angles if you want. Also, for working around non-removable world objects, having prefab corners that only snap into position in one direction can really screw up a design plan. Lastly, the stairs.. oh my god, the stairs.. There are only 2 types that connect to a preset second level floor height, based on the height of the prefab walls and flooring/second floor flooring. Base building is an awesome idea, but nearly broken for these reasons and awfully made. Needs an overhaul!