Cells created using differently aligned proteins
The problem with this is something called the structure-function relationship. The function of a protein or enzyme is completely dependent on its structure. For example, take a look at this representation of the active site of chymotrypsin:



The side chains of D102, H57, and S195 all need to be in a perfect conformation in order for the enzyme to function properly, with the hydrogen bonds being essential. If any one of those amino acids was in the D-form, the enzyme would lose its activity completely. Having every single amino acid in the D-form wouldn't help either, as the entire protein's structure (and hence its function) would be altered.