i own one -- Cameo Silhouette. heck YES it's a great machine. extremely precise. i was expecting that the software it came with would be all baby stuff -- it's not, it works with infinitely scaleable objects lile Adobe Illustrator. it can deal with making radius's (ok, radii) in corners, overcuts so that insides fall out, tracing edges.

it will also cut vinyl sticker material all day long -- make your own repro stickers.

i've made cheap stick-on stencils using self-adhesive drawer/shelf lining vinyl; it's a little bit involved (need to put a temporary sticky sheet over it to place on the fender or whatever), used aerosol paint over the negative, then peel the stencil off.

it takes some practice to get all the details right, like cut depth, placement, multi-part stuff, etc. i just set the cut speed slow; i'm in no hurry, i'm generally only making one or two. i got butt ends of  rolls of pro sign vinyl from a sign-maker store. it's a tool and a skill. but once you work them out the machine is quite repeatable.

yeah, headgaskets, forget it. the Silhouette would cut thin paper gaskets like oil pump gaskets, but it won't cut thick stuff like oil pans, or any of that hard stuff. but in my experience the toughest ones to get/make are the precision ones, specifcally my 195.6 oil pump gaskets, that determine gear end clearnace. headgaskets are special, composites etc.

the machine is precise enough that maybe if you're patient you could cut the same shape more than once at increased knife depth. personally i'll just stick to paper. Permatex Right Stuff for oil pan, side covers, etc where it simply doersn't need a paper gasket at all.