I just made one of these a couple weeks ago to assist in my Black Hole repairs. The drop target fuse that kept blowing was a 2A sloblow. The smallest breaker I could find was a 3A in the Gander Mountain boating supply section, but it worked fine for my purposes. Soldered on a blown fuse and it probably saved me about 10 fuses before I figured out the issue. Great concept. Of course, I wouldn't want to put a 3A fuse permanently in a 2A location, but for troubleshooting it was extremely helpful. Found it less pyschologically damaging to blow the breaker than to keep replacing fuses, and that allowed me want to troubleshoot longer without getting frustrated.