Here is a nice 12AWG blade fuse holder for use in your basic 2wd robots.
The fuse should be installed on the positive line just after the battery.
Takes the standard blade fuses you find in cars.
Suitable with 40 amp fuses at 32v. (Automotive)
For bigger power bots I recommend going for higher amp fuses (60/80) and using MIDI fuses either with a holder or bolted to ring crimps and insulated.
Remember to calculate the fuse rating based on your lipo battery C rating, and choose a fuse lower than that but more than your stall/robot usage.
To calculate the fuse rating, take the maximum C value and multiply it by the number of amps delivered by that pack. A 3S 3000mah with a C rating of 45 will provide 45 x 3.0amps = 135 amps so a fuse rating of 100 or 80 will be fine.
That being said, I run my 2wd pusherbot on a 40 amp fuse. 20 amps blew out.
For higher powered fuses, check out my 60 amp midi fuses here: (coming soon)