I was wondering if it is possible to use double pointed needles as straight needles for flat knitting if you put an end cap on it? I am asking because I plan on buying a set of interchangeable round knitting needles and a set of DPN. However, I found that the interchangeable needles are on the small side and I want to be able to have longer needles as well for larger projects and thicker wool since thicker wool= thicker stitches= less stitches on the needle. I can't buy a separate pair of longer needles because it is too much money for me. Thanks!