I just want to take a moment to plug CVS Liquid Nutrition Plus. Though I've been DIYing for a while, lately I've been pseudo-homeless (grad student with no apartment) and it's made it hard to keep my DIYing going. CVS Liquid Nutrition has really saved my butt. It's full of sugar, which is a downside, but it's affordable (unlike say Ensure), it doesn't give a calorie deficit (specifically the "Plus" version doesn't), and it tastes very good, which makes it easy to keep drinking it. It has no fiber, but I haven't run into any digestive problems yet. (And if I do I can just take fiber!)
DIYing is genuinely a pain in the ass. It requires a ton of research and a ton of upfront financial investment, and once you've done that you'll probably have something that doesn't taste good (which might taste better with work). For me this is a great alternative while I'm waiting for Soylent Corp. to ship.