The Spider Tie system was developed by a Utah contractor who had trouble getting small foundations done. Its intended market is builders and remodelers who want to do their own formwork. The system uses the open-web internal frame supports found in ICFs to support site-built plywood. The ties can be used to form flat or curved walls (the latter have two or more layers of thin plywood facing), or even lightweight concrete roofs. Cost is $135 for a box of 100 ties, or a little over $17 per running foot of 8-foot-high wall.
Spider Tie, 866/752-3950, spidertie.com.