When I bought my laser this is what I got for doing wiring modifications: https://www.amazon.com/Fermerry-Stranded-Flexible-Silicone-Electrical/dp/B089CW7YSR/ref=mp_s_a_1_4?crid=3LDHDJSIGYK1X&keywords=18+awg+multi+pack&qid=1676227539&sprefix=18+awg+multi+pack%2Caps%2C160&sr=8-4
But yeah that 18/2 will work perfectly. It'll look cleaner than single conductors.
Out of curiosity, what voltage are you connecting to your limit switches? 24v dc?