Li-Ion 26650 battery holder
The problem with 26650 batteries is they're not normally intended to be interchangeable like AA batteries.  They are most often found with solder tabs spot welded to the ends and either hard wired into a battery pack (such as for a laptop battery) or soldered direct to a PCB.

Being rechargeable they don't need replacing, so there is no need to add the expense of a battery holder.

However, that doesn't mean it's impossible.

You can buy PCB mount contacts for AA batteries, which are similar in size, such as these: http://uk.farnell.com/keystone/590/battery-holder-aa-n-1way/dp/1339844 and build up your own battery holder on a PCB.  You may need to adjust the sprung leaf a little to get to the right level for the battery contact, but it's certainly a possibility.  You would, of course, need some side support to keep the battery in place, but I'm sure a creative mind like yours could come up with something that would work.