Easiest way is to set scaling type to nearest neighbor, and then image size up by a whole-number multiple.
Of course, you should only do this for display purposes, really, and not work at this new higher res.
Nice work, the animations especially. They're limited, but they read very well. The chalice I think could use a bit more of the dark shade, and some highlights popping up on the back rim as well. The glass on the windows fades a bit too well into the frame, a few lines here could help with that.