Tamperproof One-Way Slotted Head Screw Removal Tool - Kimball Midwest
Polly: a tool to remove carriage bolts. - HomemadeTools.net
How to remove carriage bolt installed into a metal from outside - Quora
Bought carriage bolts and t-nuts today, thinking I was being smart about a clean fastening system for some garden furniture. Got all the way home before I realized how stupid that was. :
How to Remove a Rusted Carriage Bolt - Pretty Handy Girl