sure I can. Check the home stores around.
- birch plywood looks sometimes not so good, it's often compared to the IKEA style. They use it a lot.
- beech plywood comes in 1/4" (6mm), 1/2"(12mm) and also in version of 1/3" (9mm), which is in US hard to get but in Europe regular. really nice to cut.
- beech wood in 3/4" (18mm).
- spruce wood in 3/4" (18mm) - cheaper, but here you have to check to not have to much marks in the wood.
Also - check out OBI, they had 3/4" (18mm) acacia lately. It's the dark brown wood - the color can easily be removed during simple pre sanding. pretty colorful wood, not always that easy to cut (differing temper). Looks really neat when oiled.
oh, and do you have some "Praktiker" around? they have birch ply in 1mm , 1.5mm and 2mm (1/32") at a reasonable price. Should work fine for Christmas ornaments.
Torsten from Munich, Germany