Edit May 2023: unfortunately the quality of the prints is inconsistent. From the same photo you can get a completely sharp print one time and a visibly unsharp print some other time. I even had a case where two copies of the same photo in the same order led to one print being sharp and the other not.
I’ve been looking for this since 2021:
At myposter.de you can order photos on Hahnemühle paper, and each set can have as many different photos as the set has pictures.
They look amazing!
The rectangles are 13×18 cm, the squares in the header picture are 10×10 cm.
For the moment, myposter delivers to the following countries, each with its own URL:
Germany; Austria, Belgium, France, Italy, Liechtenstein, Luxembourg, Spain, Switzerland, The Netherlands
If you have a delivery address in Germany, use it: not only are the shipping costs lower, also the products themselves cost much less than on the Swiss site.
Subscribing to the newsletter gets you a 10% discount code for your first order.
From then on you’ll get a discount code for 15% for your next order.
Quality control is included in the price.
My wishlist, so I could sell the photos as postcards:
- For each set of photos, allow one text on the back of the cards.
Photo Matt Fibre Duo 210 can be printed on both sides.
This might also lessen the bending of the cards a bit.
But let me decide where to put the text and how it should look.
In my case, it would just be a few lines in the bottom left corner. - An additional bigger square format; 14,8 cm or 13 cm
- A 2:1 format, for example 10×21 cm
- A way to prevent the cards from bending so much. I’d be willing to pay extra for this.
- Price of each card would need to stay under € 1.00
manu schwendener 
Cool, vielen Dank!
:-)