For those trapping crayfish, how did you alter your traps to make them legal? I'm a bit leary about cutting a new trap with sidecutters to add an access hatch.
Generally it is fairly easy. One of the best ways is to add rot cord is replace the hinge on the door openings with rot cord aka cotton string. If you are using the common two piece cylinder style is gets a bit more tricky but a good way is to use a small bungie cord with one of the hooks cut off and retied with rot cord. When the cord deteriorates the bungie will release. Use this bungie to hold the trap together.
Also, I have made my own traps but also use a few I have found at garage sales over the years. Terry Bullard's traps work well and if you are looking at making your own that is a good place to start for ideas and trap styles.