Exactly! After losing 500k+ of stuff from here to some stupid hacking stealer, I never want to have to deal with that mess again. We'll setup more proper locked chests later (there are 4 just outside the shot), but we first need to build the place for them to go. This seemed like an easy way to store a way too large amount of shulker boxes.
What you perhaps failed to realize is that minties are quite attached to slimes (they are our kinfolk, after all) and upon the scent of their slaughtered blubber reaching our noses we are wont to immediately appear on the scene and steal everything that we can as retribution for the deaths of our comrades. ¡Viva el cieno! ¡Viva caos! ¡Viva sweet, sweet revenge!
Adds a whole new meaning to the classic Ghostbusters phrase "I've been slimed..." If you need an easy way to lock things up then polished stone variants might be better. So: polished andesite, diorite & granite are all protected blocks, and (relatively) easy to come by in the overworld. Just dig out some stone and then use your personal 2x2 grid to get the polished variant.
The reason why I prefer slime blocks is that they can be broken without a pickaxe - and not all accounts always have pickaxes there (still in the process of making everything). And it sounds fun.
The first reason is what I assumed when I saw the picture and had considered it for some seconds; the second reason however is much better. However, considering both reasons... wouldn't honey blocks be an even better alternative?
I genuinely have not yet seen a bee or honey yet in minecraft, so for me, not yet. We actually took a shulker filled with slime blocks to the outpost, as they are often useful in redstone things - and clearly also for securing your stuff.