So many ways to go here. If you have the Lee already, get their Zip trim or use the linked to parts. You can also use the Lee trimmer in a drill press with that chuck and shaft. Hold the shaft in a vice.
Possum Hollow and WFT trimmer in drills for similarly square trimming are fairly prompt. If you want simultaneous chamfering and deburring, then the RCBS 3-way cutter, the Gracey trimmer, or the Giraud trimmer (what I have now; works great).
Follow Clark's example and go to YouTube for videos of all these things in action and decide what's best for you.
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