Finn Juhl ottomans  

DrPoulet,
The cost to have a professional recover the ottoman appears viable when compared to your estimated value of each piece (plus your unknown acquisition cost). In other words, you will not have too much money invested to achieve a reasonable return should you decide to sell.
The worst that could happen doing your own work is minimal and easily corrected. The best case scenario is a perfect job and the resulting satisfaction
Congratulations on the acquisition and best of luck with the project.
I did not forget you helped me identify the production number of my Kaj Franck B1 teapot for Arabia.

Have you considered finding that dealer and seeing if a ottoman for chair swap can be arranged?

Thanks both for your help.
@niceguy: I paid 100€ a piece which I believe is a good price.
@ leif: very good suggetsion! I did not think about that as my plan was to use them as stools. They are pretty big and confy and do not specially look like footstools.
The seller and the dealer to whom he sold the chairs are 700 km from me so that makes things a bit complicated. Anyway, I can still have one redone and wait for an opportunity to pop up closer to me.
I guess the chair is more valuable but the ottoman has be somewhat rarer. N

DrPoulet,
Excellent...
I prefer your plan. The ottomans you "have" are far superior to the chairs you "may" acquire.
I fear the "rules of diminishing returns" will begin quickly pursuing items not readily available (undefinable transaction at a great distance).
They look to be great users. Congratulations.

If the tops are removable then re-upholstery looks like it will be pretty simple, just stretch and staple new fabric. You can make it look good enough within a couple/few tries, probably. I'd give it a shot. I think basic instructions are pretty much the same as stretching canvas over a frame, stretch, staple the centers, and then work around the edges.

Objectworship has the basics correct. This is one of the easiest upholstery jobs but it will help a lot if you are good at detail and are meticulous.
You should get latex foam if at all possible. It's pricier but worth it for the resiliency and longevity. It will eventually dry out like the original did but urethane foam will get compressed way before latex foam will dry out so it's worth it. If you can't find latex, then get the best quality urethane foam possible. Dense is best.
I cut the foam up to an inch bigger on each side than the size of the frame top, then undercut it with a razor so that it will wrap around the frame without any extra bulk. Use a high quality spray adhesive to anchor it as needed.
Choose a good Danish wool. I don't know what mill end sales are like where you are for fabric but there is a ton of it in the US and you should be able to find a few yards of the right fabric from a retailer who will ship it to you. Even with shipping it'll come out to less than retail, I think. Prices for mill ends are almost always below wholesale.
Make sure the grain is lined up parallel to the edges of the top. Skewing the grain is a telltale sign of an amateur job.
Make sure the fabric tension is perfectly even as you staple or tack it to the underside. It helps to just smooth it with the flat of your hand rather than tugging it into place at each tacking point. Look at it from above to make sure the edge of the ottoman is smooth.
The squarer the corner, the harder it is to get the fabric around it neatly and cleanly. There will be tucks but you should aim to keep them as small and uniform as possible. Choose a fabric with some give on the bias and also NOT something very bulky! But not something super smooth and thin, either. Hallingdal by Kvadrat is ideal but there are other Kvadrat wools that are great, too.
Do as much temporary tacking as you need. I do this by stapling at an angle so that one leg of the staple is only halfway in, thus making it really easy to remove it.
The above steps are what you need to do for a good look in the end. If it sounds like more than you want to tackle at this point on these pieces, then by all means have a pro do it! (but make sure the pro will do it correctly, too---there are hacks out there.)
Good luck!!

The Japan chair I have seen with original upholstery had the upholstery applied with tacks, not staples, for what it is worth.

@ Leif. Completely by accident, I found the dealer that bought the chairs. I offered a deal but he was not interrested.
Anyway, I am having them profesionally reupholstered as I got an excellent price. I chose Kvadrat Hallingdall 227 for both.
Will post pics here when they will be done.

Oh and I wanted to share these nice Japan chair ads with you guys. The first one is from Mobilia #69 - April 1961. The second one is from Mobilia #70 - May 1961.

I have just picked the ottomans and they look fantastic now.
Reupholstery is not mine but I did refinish the wood.
Hallingdal 227 was a nice choice.

Wow! Perfect!!

Update. After some negociations with the dealer who bought the chairs, we agreed on a fair price for one chair. I sold some stuff and... voila! The wood needs to be refinished and the chair needs new upholstery (it is in a fair condition anyway). So happy I have reunited the ottoman with its chair...

Superb, DrPoulet!
Consider enjoying the chair as-is (not reupholstering to match the lovely ottoman). They make a sweet couple.
Yes,
Aunt Mark

I am glad to hear they have been re-united. They are a good pair. I hear that a Japan series ottoman also goes very well with a Chieftain chair.