Small boxes and trays--how to attach the bottom?

[Phisherman]

I am building a series of various (Shaker replica) trays. These are of various sizes and woods (pine, cherry, walnut, mahogany). All have solid wood bottoms and the largest is walnut (30"x17"). How were these bottoms attached to the sides, and allow the wood to move? Cut nails?

[dadiOH]

Don't know about Shaker particularly but a conventional way is like a door panel...skinny down the edges of the bottom (if necessary), insert in grooves of front, back and sides, grooves are deeper than width of bottom.

Another way is to rabbet front, back and sides and attach bottom as you would a table top...sloppy screw or nail holes in the expansion direction plus space at the sides.