I used these dual QDs from USPlastic they are 3/8" barb and 1/4" flow but they seem to work well. They are also kinda spendy but you only need half as many.
https://www.usplastic.com/catalog/item.aspx?itemid=118169
Here are a few pics of my motorized cereal killer. I wanted it to be simple and compact. The drill speed is a little fast but it doesn't seem to effect the crush very much. All I had to do you mount it up was put a 1/2 spacer under the mill for the right angle drill to align with the shaft and...