Which paint and glue to use for a golden walnut? My goal is to craft a "golden" walnut by painting two empty shell halves and then glue them together. 

So, my requirements on the paint are:


color will be golden if this matters
should not smear off
should not hide surface nuances
somewhat water proof, but not expected to be put into water


Then, I'm going to glue the shell's halves together. The glue must be reliable and yet allow though to easily open the shell (one time is enough, but if you could stick the halves again, that would be awesome).
For “medium- to large-scale production” (e.g. making golden walnuts as tree ornaments), we’ve successfully used both golden craft paint and spray paint. Especially the latter is a bit messy, but retains the surface structure very well.

Glue the halves together (wood glue or standard white craft glue will do), sandwiching a ribbon loop as hanger in between. For the spray option, protect the ribbon with masking tape, loop the hangers over a kind of rod, lining the ornaments up with a bit of distance in between. Spray, either outside or with a large cardboard box put on end to catch the excess paint. Let dry while still hanging on the holder. Remove tape, done.

For a hanger-less version, push a toothpick in the part of the shell where there’s a little natural gap, stick the other end in a piece of styrofoam or similar.