Once you can master a DIY calculator (I use juice me up), it's a piece of cake. The calculators take all the variables into consideration, forcing you to consider all the variables. Once you understand all the variables, then, yes, it's very easy. I've heard some good things in this thread, and some things which are completely inaccurate. Like others said, head over to the DIY section. I found that once I chose a good flavor vendor (The Flavor Apprentice in my case), I was able to find a thread on the DIY section on their juices. Some threads contain starting percentages for flavors. That was the hardest part for me. Some flavors need 1%, others 15%. How can you tell, other than to make 15 different batches? Starting flavor percentages was the key for me, and allows me to adjust up or down in a couple of batches to get very close to my desired result.
The most important part of DIY'ing is to be patient. It took me six months to get a "feel" for the juices. I really thought I just sucked as an "artist" on mixing and almost gave it up. I had spent so much on gearing up, though, that I couldn't quit, kept at it, and now can often make vapeable stuff on the first attempt. It takes a while to learn that a little of this, and a lot of that are what may be required to make a good juice. When I say a while, it took months and months. So, be patient. Master the DIY calculator and learn all the variables. Event the gear you select will affect the recipes. Sometimes, with pipettes, for example, 40 drops equals 1 mil, not 20 drops. It depends on your gear and measuring equipment. But, just knowing about all the variables is nigh impossible without a good calculator. The calculator also allows you to keep track of your concoctions, just in case you nail one.
That being said, many vapers slap together a nic base PG/VG blend and then add flavoring. That can work, but it doesn't convert to percentages, and is not easily communicated to others, let alone easy to record recipes accurately for reproduction. I was a nerdy scientific approach to it initially, sans lab coat. Not anymore, I don't perfect everything to the drop, but I get very close, again, this just comes from making a lot of juice. The thing that made the most sense to me, is that I can make juice so cheap, that it still works out cheaper to make an unvapeable juice, than to buy one that sucks. I make batches in 4 ml quantities to experiment with and continue to adjust until I find something that works. I will say that my best juices often take me a month or more (including long steeping times) to get just right, so, again, please be patient. It takes anywhere from a few days to a few weeks to properly steep the juices. I have some ten ingredient juices that just come to life after 5 weeks of steeping. I know, sounds like forever, but it is, what it is. I know all about speed steeping too, but I have the patience to just let it play out. Juicing is more than half the fun of vaping after you get the vaping gear you love and use.
So, to answer your question, technically it's easy, once you have the right gear and calculator and an understanding about all the variables. Until then, though, it's not easy at all, if you want to make something with more than one flavor. Throwing a 15% flavoring of a single ingredient is a piece of cake, but since we're playing with nicotine, it's best to be very accurate, than very sick. Best to you!
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