Butter in a Bottle

So awhile back you may remember seeing something about making your own butter out of heavy whipping cream. At least you may have if you travel in the crafty circles of the internet. I saw these multiple videos and blogs and it seemed so easy like wow butter's kind've expensive, and I have arms, I can shake things. I'd like to give this a shot. I always thought it was super hard to make butter that it took like hours of labor and fancy unknown variables. But nah it's super easy.
I was at the 99 cent store and saw a little carton of heavy whipping cream and figured eh what the heck let's try it. It's been sitting in my fridge for a week when I spotted it while food browsing. So I popped it in an empty water bottle and added a bit of salt and started shaking it. At first I was like this is doing nothing... but then I noticed it was coating the inside of the bottle much thicker than before. Soon it felt like it was all foamed up and wasn't moving at all so I took a moment to rest my arms because fawk they got tired quick. (And checked the interwebs to make sure I hadn't fucked anything up because i hadn't checked anything beforehand just went ahead and did it from memory) then continued shaking and then plop it started separating. At first it was this weird watery buttery mixture that looks like when you try to scramble something like sour cream into raw eggs. But it started to clump together after throwing it around in the bottle a bit more then I unscrewed the cap and poured off the buttermilk. (Which keeps draining out of your butter for a bit.) Cut the bottle open and drained more buttermilk off and tahdah! Butter was born! It's a very nice soft whippy butter that would be nice to put on bread or something. I want to try this again with herbs and shiz in with the cream so I can make flavored butters. :o Italian herb butter, cinnamon sugar butter, fruit butter...