I've got these:
I'm in a manufactured home, and a dropped kettlebell would go through the floor, ground, and straight to the center of the earth. Outside is a mixture of dirt, rocks, weeds, grass, and rodent droppings, so I set the blocks up and tear them down when I workout. The blocks store behind the kettlebells quite nicely the rest of the time.
For deficits, my gym has 1" thick rubber mats that you pile up to achieve the desired height. I had mats like this in my work space that could be portable enough to bring to the gym with you. Or a bunch of my friends with kids have similar squares with the alphabet on it.
If you're a cheap ass like me, you can use those foam fatigue mats from Home Depot or Amazon (the kind you stand on). You can do your entire toolbox for the cost of one sheet of Kaizen.