There are a lot of choices when it comes to the end plates of a concertina.
On an instrument with wooden end plates, I usually use a decorative veneer on the front, a cheaper hardwood (e.g. maple or beech) veneer on the back, and a core of solid sycamore. The grain of the outer veneers (unless it is a burl) will run perpendicular to the core, which improves the strength and stability of the board. I glue the layers together with epoxy resin to avoid injecting water into the board that would cause it to warp when it dried.
For example, this is a laminated amboyna burl board for one of No. 8’s end plates:
The most basic option is simple flat wooden end plates with a plain black veneer like No. 11:
Or flat nickel silver end plates with a crimped border like this Crabb Anglo I restored:
No. 12 has flat wooden ends with a fancy Amboyna burl veneer with red stain:
No. 6 has inset raised ends made from nickel-plated nickel-silver:
No. 8 has flat amboyna-veneered ends like No. 12 but without any stain:
No. 10 has inset raised metal ends like No. 6, but made from polished aluminium alloy:
So far I have only shown traditional Victorian-style foliate patterns, mostly designed by myself. No. 7 was particularly special to me; it has raised wooden ends with a non-traditional oak tree and butterfly pattern that I designed in collaboration with the client:
No. 9 has flat nickel-plated end plates with two very different fretwork designs provided by the client (photos taken before polishing and plating):
This design in particular was very time-consuming to hand-pierce due to all the nooks and crannies.
No. 1 was also a bit unusual. It has flat wooden end plates, but I tried to imply a 3D effect with the geometric design (you can tell that my piercing and French polishing skills have improved a lot since I made this one):
I have also worked with a professional illustrator, Nina Dietrich, on two end plate designs, for No. 3 and No. 4.5. No. 3 has flat wooden end plates with a rippled maple veneer, and I used pyrography (wood burning/pokerwork) to add black lines to enhance the 3D effect of the knotwork design:
No. 4.5, also designed by Nina Dietrich, has flat nickel-silver end plates, using hand engraving to mark the lines in the design: