If you decide you want to stick with the gshield for the time being, you can buy it here. It’s the same one Inventables sold except this is direct from manufacturer. $50
All you need if you have the power supply and Arduino is the shield from this page and 4 TB6600 drivers.
second that. and good customer support. he even will walk you through stuff if you get stuck.
Try to order a delrin nut from Inventables. Or a 17 nema motor that has a custom shaft made specifically for their older model machines. I can list numerous parts that Inventables no longer stocks and will not make to support the machine I have. If they ever upgrade the Machine they are currently selling they will purposely engineer changes that eventually cause the older machines to become obsolete. Just like they have in the past!! The least they could do is support and stock parts for those of us who believed in this company to begin with.