I have made several puzzles like this for people close to me.
They provide me with a photo of their kid(s) that they really like,
and I make it into a puzzle/conversation piece.
This small puzzle was the first one I ever made. This
was made using ¼" cedar. The photo measures 3.5" x 3.5". The base
is ½" thick in the center (made from two layers of ¼" glued together with the
grains in perpendicular directions) with another ¼" thickness forming the border
to hold the pieces in place.
I left this puzzle bare, with no stain or varnish. Once
sanded, the cedar was extremely smooth and it smelled great. It's hard to
improve on that, so I didn't try.
This larger puzzle was made out of poplar. The photo
measures 7" x 9". The base is made from a ¾" thick piece of poplar with
another ¼" thickness forming the border to hold the pieces in place. The
puzzle is finished with two coats of stain (golden oak) and one coat of varnish.
I used contact cement to adhere the photos to the wood.
Then I used a scroll saw to cut the photos into the puzzle pieces.
I used a bandsaw and a belt sander to get the outside edge in the shape
that I want.
Most of the recipients of these puzzles, I think, have them
displayed more as conversation pieces rather than as toys for the kids to play
with regularly.