Using the repetitive motions of making stone tools now could be good for developing manual dexterity. It might also give you time to reflect on the value of crafting while your hands stayed busy. But, lacking context, you might not get the same benefits from the work that your ancestors did.

Making stone flints now means separating the activity — stone tool making — from any original context(s), which would have been complex and social. What would an ancestral stone tool maker have needed to know, back in the day? To have the full benefit of stone tool making, I imagine the knowledge of literal hunger, at least some of the time, would play into the seriousness of the work. Humans lived in group/bands/tribes and were unlikely to be off on their own practicing in solitude for hours, others would have been near by, possibly working in parallel or tandem, or offering suggestions (verbally when there was language, perhaps gesturally before that). The stone tool maker probably included expertise at learning which rocks worked best and figuring out where those good rocks were found. 

Having worked a lot with my hands over many years, never from physical need, I truly wonder how that would impact the making.