I hope this comes across as pseudo-inspirational, and not bragging. It took me some time, and many different builds to solo craw, but I managed to do it with all 4 classes, and semi consistently.
If the old forums were up, I would link to my Mordy solo craw guide. These were the main things I did to make it doable.
First and foremost, especially if using a masher to take out Craw’s purple spots, I highly recommend using a ranger COM. Best option is a purple with +4 to predator and the extra crit damage 5th line. This lets Bloodwing be on a 1 second cool down so OFB (w/ explosive element) is always ready to heal. Keep throwing Blood out, and have Bird of Prey maxed out, so you can always have health return by recalling him.
Since I preferred ranger to gunslinger (the extra fire rate made it harder to land shots on Craw with a revolver/masher. I preferred ranger so each shot hit harder), and I didn’t have ammo regen, I tried to mix my 4 guns between revolvers and machine pistols/repeaters. My masher main (2-shot preferred for extra damage) and corrosive option I usually kept as revolvers, and fire and shock as pistols.
For shields, I used a tediore quick health regen with the shortest recharge delay I could find. I eventually got an anshin rose, and it made life easier.
When coming off the lift, I would toss out Bloodwing, run for the right set of pillars, and take down maggots first, then greens, and keep circling the right pillars. I would take shots at Craw when I could, and keep taking down minions until only purples remained. I wasn’t perfect, but I could fairly consistently solo craw with this set up. I know some of this info has been mentioned already, but I hope you find it helpful. Good hunting!