This is really pretty, I love it! Trying to think, for those of us who can make broad brush strokes but really can't paint in detail... maybe cutting out a silhouette of a tree or similar and sticking it on the jar might work?
I don't know if you already find out what it was, but just in case you haven't (and someone else is wondering) that was glitter glue. You can find it at the 99.
I think you can but oil colors need so much longer to dry as acrylic colors... you have to let it dry maybe 4 weeks... I used acrylic colors for this because they dry in 5 minutes and you can paint with acrylic colors on EVERYTHING