If you can't find a single 18650 sled but can find double or triple then you could cut them with a dremmel tool down to hold just one battery.
Also if you have a hard time finding a sled you could make your own using a hardware store spring--machine screw--epoxy glue--little piece of plastic or wood--a contact from
an old battery charger.
This is a do it yourself pic--of what I did to get around not having a battery/sled-------
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