A simple fuse can not prevent harm, but with a current limitation is you can experiment much more flexible and carefree.
Here are some links to circuit concepts.
Here you will find Schematic Circuit Diagram for DIY and further information on Current limit
|Simple current limiting with transistor or FET||www.atx-netzteil.de/strombegrenz_spannungsreduz_led_anschluss.htm#Blatt%201|
|Retrofit current limit for the laboratory network devices||www.zen22142.zen.co.uk/Circuits/Power/add-on.html|