I've made a few battery packs for lamps by just soldering AA NiMh cells together. Not had a problem yet - although the heat can't do them any good. I use a 400w 'pistol style' soldering iron to do it quickly.
However, if you get tabbed cells you solder the tabs together and the cell shouldn't be subjected to heat anyway.
The issue will be identifying the cell size, I suspect. The proportions look like
Sub C, but it should be possible to check the dimensions against other sizes.
Of course, it's highly debateable whether it's worth the trouble. I've always felt n+1 applies to tools!