I built a new COB today!
100 Watts Cree CXB3590 3500K dimmable.
I already had most of the parts, so just ordered the chip and reflector.
The Heat sink I already had is massive @ 6 & 3/4" (17cm) so should do a nice job of cooling.
I made this as a spare for one of my 2' x 2' (60cm x 60cm) tents.
I have a new MICRO light turning up any day now This COB will be the back up to that!
Pictures...