Special equipment: a round plastic crudite platter, a fluid transfer pump (see Cook's Note), a bundt pan and a large slow cooker
For the volcano: Use a round plastic crudite platter for the base of your volcano and cut a small hole in it large enough for the hose of a fluid transfer pump to go through. Snake the depositing end of the pump hose through the hole in the platter. Invert a bundt pan over the platter, snaking the hose up through the hole in the bundt. Cut a hole in the center of the tomato half, then insert the tomato cut-side up in the top of the hole in the bundt pan, pulling the hose up through the hole in the tomato and pushing down a bit on the tomato to snugly plug up the hole in the bundt pan with the tube inside.
"Paint" or "spackle" the sides of the bundt pan with the cheese, using an offset spatula or rubber gloves. Then layer the chips on top of each other around the bundt, starting flat but angling as you go up, sticking them to the cheese. This creates a volcano look.
For the decorations: Arrange your accoutrements however you like. I put a lot of diced tomatoes and beans around the top to make it look like a caldera. I also liked incorporating cilantro stems and broccoli florets at the base of the volcano, as they look like trees.
For the cheese sauce: Turn a large slow cooker to low while you prepare the sauce on the stove.
In a pot, combine the sodium citrate and 3 1/2 cups water over medium heat and bring to a simmer. Once simmering, add the cheese in handfuls, whisking until incorporated before adding the next handful. Once all the cheese is incorporated and melty, add the sriracha and use an immersion blender to blend to a uniform consistency.
Transfer the mixture to the preheated slow cooker. Place the receiving tube of the pump into the cheese sauce and slowly and carefully pump to create "lava." Note: The cheese sauce might splash, so use with caution and put in a safe location.
Fluid transfer pumps can be found at most home improvement stores or online. Sodium citrate, a sodium salt of citric acid, helps emulsify the cheese sauce. It can be found at speciality food stores and online.