For FDM type or SLS printing I'd guess "no" even if the material itself was food safe. The reason becomes clear under a microscope. These kind of prints are extremely porous, and though maybe water tight, bacteria would absolutely thrive in all the micro-nooks and crannies.
SLA materials don't have the porosity thing, but I'm not finding any 'food grade' SLA materials right off the bat.
Probably the safest bet is to print a teacup mold with whatever process and use it to make teacups out of silicone or other food grade material that can be made in a printed mold.
could anyone explain me difference between 3D printing and prototyping ?
3-D Printing is used in prototyping, it helps you get a prototype faster, with metal and plastic filaments, it gives you the freedom that mold making doesn't, especially regarding speed. That's for prototyping, it is usually not utilized in full scale manufacturing and operations, molds are usually used, you may be able to 3-D print molds, they are usually machined on CNC machines though. 3-D printing is utilized in prototyping because it is faster and cheaper than wasting metal/other materials on molds, its cheaper materials, and faster for an effective prototype. While metal molds are faster to pump them out when mass producing them. Overall, 3-D printing for the prototype process, and molds for the full scale production.
Using PETG and coating it with a foodsafe resin/epoxy is a pretty easy way of getting a foodsafe final product. PETG itself is foodsafe and resistant to higher temperatures and UV, and coating it with a similar material solves the porosity issue.
Yes, you can get the best-quality, food-safe PLA 3D printing filament at ‘3D Printers Bay’ at the most affordable costs. Besides PLA, you can also get food-safe PETG filaments and all kinds of 3D printers and 3D scanners.