Clean cardboard boxes can work just fine (though disposable when they get soiled or damp)- cereal & cracker boxes are often the right size/shape. The advantage of the hides sold by Reptile Basics is that they have more weight to them- when snakes go under a lightweight cardboard box, it can easily lift up & feel less safe to them. The plastic RB hides are washable & last "forever"- and they're not very pricey at all. Other sources sell similar ones too- the Bean Farm has great herp supplies too, but depending what country you're in-?-might not be available to you either. Some ppl have converted plastic flower pot "saucers" to snake hides by cutting in a doorway, & clean plastic food containers are often used for snakes too (again, cut a doorway- I use a sharp box-cutter knife, or an Exacto-knife to cut.) Food containers -if used- are best if not see-thru though- it's harder to find opaque ones. But yes, many things can work- be made into hides for snakes.
I assume you also know not to handle a snake that isn't a strong feeder? Handling makes a small creature like a snake feel powerless*- they're predators & they need all the bravery they can muster to go after their prey- especially while they're learning-practicing-& feeling stronger. *Keep in mind that the only thing that picks up a snake in the wild is a predator about to eat THEM. So whatever you do, never handle a snake before you feed them- not if you expect them to eat.![]()