Nice work, my boy!
I have thought about picking up an XS650 for a project myself, lots of stuff to do to a bike like that.
On your first battery box you made, the end melted because you were carrying the heat into an area where there is little metal to absorb it. Start from the outside edge when the metal is cool, and you will not melt the ends like that.
2007 Kawasaki EX650 street/track 636 forks - Hyperpro shock - Woodcraft - LeoVince - Dynojet
2003 Yamaha R6 race/track Ohlins - Arata - Vortex - Woodcraft - Dynojet
OMRRA Expert # 440