ok so this may be a little much and not exactly what your looking to use since it doesnt use your existing setup but maybe it will be of some help to you. so i recreated your setup but in a modular reusable way. the idea here was that you can switch out the mesh and the material based on arrays. the number of spheres showing the material options would update according to how many materials are in the array. the short of this is you can use this actor as a master for any type of furniture (mesh) and apply any material to it, if you want a couch you can create a child of this master and add couch meshes to the array.
anyways on begin play we set the mesh and material to the first in their respective arrays. then we create the material spheres to display the material options by using a for each loop and a add static mesh, we also set the material and the visibility of the mesh here.
on begin overlap with the actor we make sure its the player overlapping, enable input to the actor, and set the visibility of the material spheres. we do almost the same for end overlap. on begin overlap we also set which sphere to outline, in this example i used a point light to light the sphere but if you look at the bottom of the second picture you will see i also included if you were going to use custom depth and post process (link to [tutorial][1]).
for switching the meshes and materials i used a simple method of using a int variable as a index or rather to keep track of the current index in the array. so when we press the 2 key we get the material index variable and increment it. then we do a check to make sure its a valid index in the array by getting the materials array, get last index, and check if material index variable is greater than the last index in the array, if yes we set the variable to 0. then we set the material of the current mesh to the one at the appropriate index in the array. after that we need to update the outlined mat sphere by using the same method we used before.
this may all look complex but its not too bad once you break it up into the little individual parts. i admit i probably went a bit overboard with this haha. if you have questions let me know.
