That looks like a really nice fairy garden container he built!
I love the fact that it's on legs so you don't have to bend down so far to work in it. I imagine it would get heavy with 50# of moist soil in it, but you're right - since you seem to be using mostly succulents, you won't want it too be very moist anyway. Do you have a place to keep it inside that will get lots of bright light? That would be a main concern if it was mine. And once it's full of soil I would think it would be pretty heavy to move. So be sure you know where you'll want it to end up before you fill it with soil!
You've already got a nice assortment of plants and accessories so go ahead and jump in on construction! I guess if you're using a fairy house or structure I'd decide where to place that first and work my way out from there. Since your plants are all in containers you can just set your containers around until you find a combination you like, and then plant them.
Looking forward to seeing more of it. You should post progress pictures here so we can watch as it grows.