Reddit reviews uxcell Round Steel Rod, 10.5mm HSS Lathe Bar Stock Tool 100mm Long, for Shaft Gear Drill Lathes Boring Machine Turning Miniature Axle, Cylindrical Pin DIY Craft Tool, 1pcs

You can use a follower on BEST locks if they close with a clip in the back (as opposed to rivets). I bought a 10.5mm metal rod on Amazon (this one https://amazon.com/uxcell-Lathe-Round-10-5mm-Length/dp/B07KYB24VF/) and it works great for this. 11mm might work too, but I wanted to have a bit more clearance.
You have to open it with the operating key or pick it to operating, then you can push out the plug with the 10.5mm follower. The control sleeve stays held into the body; you can then pull out the driver/control/master pins and springs the usual way as you remove the follower.
Putting it back together with the follower is a bit tricky: when you're putting the first pin in, there is nothing holding the control sleeve to the body so it moves around and makes it difficult to get the pins in. Once you get the first pin in, the rest go a lot easier.