There are (at least) two issues - one "actual", one "regulatory".
For the "actual" one - the metallic materials (with the possible exception of silver, depending on what it is alloyed with) will be
attacked by food. The "stainless steel" is actually a composite using bronze as a filler to stabilize the sintered iron, meaning some
copper will dissolve from it (not normally a problem, but hazardous for infants and for people with kidney or liver problems). The gold
or silver plated varieties may contain nickel or other elements underneath, depending on the plating process used. The UV-cured
"detail" acrylics may contain unreacted starting material, also they use a wax-like support material that is probably a strong laxative,
if nothing else. The "strong and flexible" nylon one has a very porous structure, so it will harbour a microcosm of its own, once some
nutrients become available.
The "regulatory" one - none of the materials (except the glazing used on the ceramics) will be bought and handled as "food grade",
with all the testing and hygienic processing that would imply.
That said, the worst you could contract from self-printed, unsealed plastic cookie-cutters would probably be severe diarrhoea (norovirus), but
I doubt you would get any official encouragement from shapeways to try for yourself. (Disposing of the cutters after use would probably
be wise - unless you want to risk contamination with carcinogenic mould toxins)