IMHO its important to provide a suitable container of washed playsand in the cage of any sexually mature egglaying female chameleon all the time so that you don't miss the sometimes subtle signs that the female needs to lay eggs.
Its important not to allow the female to see you watching her when she is digging too.
Once she starts to dig she may dig several test holes and then should settle on one hole. She should dig that hole until she is satisfied with it...it may take more than one day and she may not do it all day. She should then turn around bum down and lay her eggs, fill the hole in and return to the branches. Its okay to feed and water her when she is up in the branches...but don't leave any uneaten insects in her cage....they may chew on her or the eggs when they are laid.
After she is finished filling in the hole and has returned to the branches you can dig up the eggs. Be careful not to turn them as you move them.
I use shoebox sized plastic containers with lids. I punch two tiny holes in the lid and fill the container about half full of slightly moist vermiculite (the coarse type). To test the vermiculite for moisture, take a fist full of it. You shouldn't be able to squeeze more than a drop or two of water out of it.
I lay the eggs in rows about 1" apart in dents made with my thumb. Put the lid back on and put the container someplace where the temperature is appropriate and its dark. Beads of moisture will be seen on the lid and the sides of the container.
Regarding eggbinding...generally its related to not providing a suitable laying site or to poor husbandry or two physical causes such as deformed/fused eggs, deformities in the reproductive system, etc. Overfeeding plays a part in it.
