Alternative to idols

My first (and current) altar has three stones with runes (Ansuz, Tiwaz and Thurs) written as stand in for idols. But after consideration, I've came to the (late) conclusion that the Thurs rune is inadequate to stand in for Thor for obvious reasons. Wich leads me to ask, what alternatives to proper statue idols are there for me? I'd very much like to aquire statues of Odin, Tyr and Thor but It's Impossible for now. Currently, only the Tyr stone is in my altar, since I offered to him recently, but the other two are stored away.