Help rescue Arne Hovmand Olsen chairs!  

I would get some liquid hide glue and optionally mix in a little bit of teak dust. Fill in the holes, then sand the excess glue off after it has dried. Be careful not to sand through the veneer. Then finish as per normal. The holes will not be completely invisible, but short of re-veneering the chairs, nothing is going to get you to completely invisible.

Thanks Leif, is hide glue relatively easy to come by?

Actually just found some locally! Thanks again.

I imagine the person who upholstered the chairs didn't know how to take the insert off which the upholstery should be fastened to. Since these don't have it, does anyone have some advice as to how I could get this piece made? Here are a couple pictures of one of mine for reference:

You've lost me. What are you looking for? What is missing? Where does this piece go?

My apologies! To clarify, this curved wood insert should come on an original chair like what I am using as dining chairs now. The additional set that has been reupholstered is missing this piece. So to be able to reupholster them to match the ones I have I will have to create this piece. Pictures:

Ah, now I understand. How thick is the plywood supposed to be?

I believe it's about 1/4".

Then I think you have two options:
A. make a mold with the side-to-side curve of the plywood out of some lumber. Perhaps use a bandsaw or sabre saw to cut 2 or 3 2x6's with the curve, leaving you with top and bottom form pieces. Then glue together a couple pieces of 1/8" Luaun ply, and clamp then inside your forms to dry. Then finalize the outside shape and cut/drill the various holes.
B. 1/4" ply is usually somewhat flexible, and you don't need much flex to get that curve. So cut the shape, and the holes. Then use the upholstery to pull the panel into the approximate curve. The key would be to get the upholstery to pull it into a slightly tighter curve, or exactly the right curve. If you upholster it to a wider curve, then the upholstery will ripple when you attach it to the seat; not pretty. One trick you might use here would be to cut the proper curve in a 2x6 like plan A, and temporarily screw the panel to the curved 2x6, then you can pull the upholstery tight against that, instead of having to "freehand" it.

Another option is to kerf cut the 1/4" ply with a table or circ saw, fill the kerf cut grooves with epoxy or wood glue, then clamp the piece to original seat back to set the form. It's not the most structurally sound approach, but seeing as the piece is backed with the original ply back rest, it's should be "good enough". Note: this method doesn't work so well on compound curves.

Del! - Not on topic but I have to ask. Is your credenza marked? It looks like I've had and was still trying to figure out the manufacturer. Many thanks!!