I got the design from etsy (SVG, originally made for Cricut and similar machines). Turns out to be good for lasers, too.
The usual problem with cardboard is burned edges and ash traces on the cardboard/paper. Use high gloss paper (Clairefontaine DCP 250gr). The glossy surface makes that the ash does not stick. Blow out the cut pieces with pressurized air to avoid too much ash on the paper and dirty hands.
And finally use spray paint (or artifical snow spray) to cover any black marks/edges.
Lighting is courtesy of IKEA (VINTER battery driven string of star-shaped LEDs).