I’m not sure if I’ve seen this but I know you guys love little hacks. It’s fairly self explanatory, but you just cut the top off of a 16-24oz bottle, I used a coke bottle. And bam. It fits snugly, but is very easy to remove, but won’t accidentally get bumped or fall out while refilling your bottle. I could never find a funnel that fit well, and didn’t get clogged while refilling, then I had this genius idea. Hopefully someone hasn’t thought of this, sorry if this is common knowledge.