I reply because the mess sound familiar ^^
The first week I started using this, I had to clean an entire kitchen because I managed to shake without the lid being properly attached.
I still sometimes manage to nasty stains on my clothes when the first drip appears from nowhere right after shaking. ( wow, that sounds like a euphemism, yuck ^^ )
And I noticed the scoop tends to get magnetically charged, so if you look at the powder you’ll see pieces jumping off of it without any further provocation.
All this caused me to develop a very particular set of rituals to adding the powder, shaking and the first sip (you should see the way I shield myself from that first drop, it looks ridiculous). It mostly works, and for me it’s definitely weighs up to the downsides of this project, with the right approach and a bit of luck I can contain all the mess.
I say a bit of luck, because both the magnetic powder and that first drip are very unpredictable. Depending on the weather and other conditions my clothes sometimes hold a different charge from the powder, causing a rain of tiny dust missiles to seek my clothes, occasionally actively flying upwards. I’m wondering whether there’s a way to ground the powder in some way to avoid this. I haven’t tried it with a metal scoop.
I think it might be possible to avoid the shaker drip, though I don’t expect that to be easy. The very features that make it watertight during shaking cause a lot of the drips through a combination of surface tension and capillary action.
Smaller bags definitely wouldn’t help me. Getting the last bit out of a bag is always the most problematic part for me, where it tends to fly or stick exactly when I want the opposite. I think making the powder fall past the plastic might actually be charging it more, causing more of those magnetic issues.
The increases in bag size in the past have definitely helped me reduce the amount of powder I have to clean up from my kitchen sink.