My friend takes her largest square of shirt. She rough cuts out the part she wants puts stabilizer on the back and then squares it up to fit what she wants to save. Then she sashes it with a size she likes. That is her master block and she works by using different sashing or putting to pieces of t shirt together till they equal the size of her master block and works out from there. So sometimes she will have three smaller t shirt blocks together to equal the master. Once she had a ton of sleeves to work with and she had six pieced together with little sashing's between them till the came up to the size she needed.