Corzetti pasta stamp / cutter. See http://www.prouditaliancook.com/2013/12/making-homemade-corzetti-pasta.html for a how-to on how to use the thing. Two parts. One top stamp, another bottom stamp/cutter.
Warning/Disclaimer - use at your own risk - unknown cross contamination or poison risks with whatever plastic you use. Yadda Yadda... Rub with a bit of olive oil before use to make removal of pasta from stamp easier.
11Jul14 - updated with cleaner shape / larger bottom stamp