These are some ideas based on old sketches. I don't consider them fully developed proposals; they need work. Often I've just copied and pasted more than one copy to give a sense of potential composition ideas. I would NOT generally use multiple identical or mirror image pieces. Background represents 13'x7' wall with line at 4' to represent shelf.

(actual designs would not be rescaled versions of one another; this design may need to be simplified/scaled back to fit the budget)	I may be able to do this piece this big, if the round is flat.
(actual designs would not be rotated versions of one another)	(actual designs would not be rescaled versions of one another)
A piece with this visual weight can be effective off center on its own, too, depending on what the wall edges look like.	A serious departure.
(actual designs would not be copies of one another)	(actual designs would not be copies of one another)
	(actual designs would not be copies of one another)
	(actual designs would not be copies of one another)
	This one is a whole different style, and I include it because it's a design I've long wanted to build. However, it is unlikely to come in within the budget at this scale.