what tool does everyone use drain/fill the BA10/15

Curious to know what everyone else used to open the metric square drive fill and drain plugs? I machined down a socket extension. Is there an actual tool available? I though about going to the dealership... for about 3 seconds until I remembered how they wanted $80 dollars for a weather strip Quadratec sells for $15, or their $12 shackle bolts and $16 U bolts etc. At this point I like to price at the dealership just to feel a sense of gratification when I buy the part aftermarket for 20% to

50% of the cost (most recently passenger side E brake cable $68... $29 from quadratec).