Celluloid is still made in sheet and block form today. American Art Plastic supply it in sheet form, there is a definitely a company in Italy that make it for high-end fountain pen manufacturers, and Germany still makes it.
The German stuff is meant to be just like the old stuff - a bit unstable and prone to shrinkage. One guy bought a box of knives from Germany, celluloid handles - he found that the celluloid had shrunk on all of them.
The old stuff was prone to exploding - lots of cutlery factories went up in smoke. One factory had a hinged roof - the idea being that the if an explosion occurred the roof would lift and dissipate the force of the blast and the building would survive. Don't know about the workforce, though...
However, not everything these days that is called celluloid is actually celluloid. In many ways it has become a blanket term, like calling all vacuum cleaners 'Hoovers' so the seller may not know what he is selling - could well be a modern acrylic which, these days, can mimic celluloid very well. I ordered some sheets of so-called celluloid from a knife-making supply company in the US once - it stank of fibreglass resin and was clearly some sort of acrylic. They took it back and refunded me in full, including the big customs fees and all the postage.
Regards,
Neil