Try looking at shops on etsy.com. There are lots of handmade sleeves for iPhone 6 & 6 Plus. I used the keyword - "Sleeve iPhone 6 Plus"
In particular, I highly recommend
"SeasideSew" and it also has the following web site as well (which links to its shop on Etsy)
Http://www.seasidesew.com
You can choose from a variety of handmade sleeves/pouches and can ask the shop to custom fit your particular phone case as long as you let them know the dimensions of your particular phone case. In other words, you can get a sleeve/pouch for any phone case even those rugged cases (e.g.. Otterbox) but normally people won't do it as it doesn't make sense to have a soft pouch to protect a rugged case!
Originally I was looking for a Golla sleeve/phone wallet for iPhone 6 Plus but I couldn't. Then I found a few shops on Etsy. I bought one from another shop and despite the craftsmanship and stitching are excellent, the inside cotton material is too thin. it only took me 2 hours to see lint inside the sleeve.
Then I spotted SeasideSew and was attracted by the fact that their pouch is water resistant inside and yet machine washable. Also the inside material is high quality Kona cotton.
See my sleeve below -- this is a custom case based on two phone cases listed on SeasideSew because I couldn't find the exact one that I liked at that time and yet water resistance and Kona cotton inside material are quite novel to me.
The owner - Natalie was very patient and detailed oriented and she made great effort in making a beautiful case. Her customer service is amazing and it is extremely easy to work with. Great communication and great presentation. Couldn't find any faults at all.
Note the tab/carabiner loop on the side is of a different color than the inside material. Not her fault. She pointed upfront before starting to make the sleeve. The issue is the color choices of Kona cotton are sometimes hard to match.
It took a week for her to make the case and another week to arrive in Canada. If you are in US, it would be much quicker as she resides on the Wesd Coast
The fitting is perfect. Not loose and not overly tight. There is an ample amount of resistance at the opening of the sleeve which is good. The stitching is perfect and the construction of the sleeve has great details and the Kona cotton doesn't attract much lint and is soft and pretty sturdy.
You can custom the case and she has many fabric and patterns to choose. You can also ask her about the color of the Kona cotton inside the case, (I actually went to Kona cotton web site and let SeasideSew know about the color code.
My phone case is a Rearth Ringke Fusion clear hybrid case. Interestingly I gave her the dimensions of Spigen Ultra Hybrid Clear case (I changed my decision afterwards and went for Ringke Fusion instead) and yet it still fits.
