I remember our preschool teacher taught the class how to make chef hats, and it was pretty inexpensive. I used poster boards cut to a 6 inch height, then measure the length on one of the kiddos...once I had that, I glued the poster board into a cylinder. Then used two layers of white tissue paper for the puffy part of the hat.

First I glued down two corners of the paper opposite each other on the brim, then the other two corners...then going around the hat, and gathering in the excess paper, glued that into the brim as well (all gluing is done on the inside of the hat, so as not to be seen.)

make chef hats

Hot glue is sometimes used because of it durability for beginners one might want to decrease the chances of finger tip getting burned by just using elastic tape (just to be on the safe side).

However, it came out very cute, and has held up very well all year...we use it once a month for a special "chef" project. The children look forward to the next time we get

together on another project, As far as an apron goes...if you are looking for simple, and inexpensive, a hand or kitchen towel folded in half with ribbons sew or hot glued onto the top corners for ties would do it for a half apron...if you

want a bib apron, you would have to do a little more work...but perhaps turning the kitchen towel up and down the long way, putting a ribbon loop from the top two corners to go over the child's head, and two more ribbon ties half way down the long sides...that would probably work.
Have fun!