Yep-you can use the same technique as the flower pots,on a lamp.
This started out as one of those clay colored ginger-jar lamps.You know the ones.The type everybody had back in the 70's and 80's.A new millenium,a new lamp!
You use the exact,same techinque,as the flower pots,except you don't have to use the concrete sealer on it.You need to make sure the shells are really tight together,or you're gonna get dust bunnies in there.And you don't want that.Yuck!
Spray it well with the polyurethane sealer at the end.That makes it easier to dust(if you are so inclined to dust.......which,I try to avoid,if I can.I'd rather make things than dust,but I digress).
Let there be light!