We used fabric.js as well to create custom laser printed/engraved products. As with you, our first iteration was just standard javascript with jQuery, but fabric.js made a lot of things much easier.
Thanks! That site is like an eery Dublin-doppelganger of my plans, would be cool to chat with you about it (though I get the impression you're no longer with them).
I'm no longer the CTO, but I'm still friends with the rest of the founders and lend a hand every now and again (I'm still a shareholder in the company).
Drop me a line at malonso [at] loopbit.com if you want :)