If it’s just for display or if it’s for fun toy photography, you should go all out when making your diorama. That’s at least my opinion. I say that because the more you do the more depth you add to the character being seen. Don’t get me wrong not everything has to be extravagant but if you want to put a figure inside a world, even a corner of it, why not?? I also think diorama scale is very important, now this is mainly for photography purposes. To get the feeling that the figure isn’t just 3.75”-8” tall, you need it to be in a world with proportional surroundings. A good example is when I first tried shooting a predator outside and the fallen leaves were a massive giveaway. So here is one example of my diorama builds. Initially made for freddys boiler room type of scene, it’s become useful for a few things. I wanted it to be large so I could get far back images to give a good scale to take the idea of the “toy” away. So I built 2 walls out of 16 gauge scrap steel, and a section of a support beam system in a part of the ceiling. Then I put some piping along the walls and an extra wall to give a hallway type of look. This is just an opinion nothing more, any questions about what I did in the build just ask.