I'm sure the Ingress Engineering roller blocks work well and the price for a set of 3 is reasonable vs DIY when needing a two or three sets. If I wanted a set or two or three I'd seriously consider Ingress's product. That said, when looking at 10+ sets then DIY becomes attractive. Once opting DIY the design parameters can be changed to one's liking as well. As far I can tell stainless steel is a better option than 7075 aluminium but looks like no one posting in this thread has compared the two.