@Mike_Miller , buy the extrusion from misumi, the other parts, honestly, you probably won’t know the difference in accuracy, as long as you don’t get absolute garbage parts. Misumi motion control parts are incredibly overpriced, coming from somebody that designs these types of things for a living. You can get the same parts from McMaster Carr for crappier of you know what you’re looking for. You don’t really need the high precision ground rod, the difference in runout will not be noticeable to you.