Here are a couple of web based tools for designing laser cut boxes. There are probably others out there, but these are the ones I’ve used.
This one is good for just doing finger tab jointed boxes.
This one does flat, finger and T-slot joints.
http://www.makercase.com/
Whoa, that’s a good one.
This is a subscription one, but tons of designs
http://boxdesigner.frag-den-spatz.de/
I paid for a subscription and use it almost daily.
It is 13 euros for 12 months, so about a dollar a month.
It isn’t as fancy as that one, but this plugin for Inkscape is my goto tool for tabbed boxes.
https://github.com/paulh-rnd/TabbedBoxMaker
-Rob
I found this site just now. Not sure where else to post it, so this seems like a good place.
EDIT: duh. I just noticed the link to this in the first post. 