Shoe lifts for leg length discrepancy are my most common modification. Some people have had a lift on their shoe for years and others later in life after an accident or surgery. The purpose of it is to compensate for the shorter leg to make walking and standing less uncomfortable. The height of the lift varies but once it is establish usually remains the same making the process of installing your lift more predictable and easier to communicate. Sometimes the first lift can be a little trial and error to find the measurement that works best for you. In most cases the lift is the same at the heel and forepart of the shoe from the midfoot of the shoe to the toe the lift tapers off to a gentle rocker to help make walking more natural. In most cases I fillet the outer sole off the shoe and build the lift between it and the shoe upper. I can put a lift on just about any shoe you'd like although I recommend new shoes that support your feet laterally. Tie shoes are best but slip-ons will work fine. Sandals with more straps are better than less but I've put lifts on flip flops too. You need to be able to walk confidently in your shoes without worrying about falling off. I use EVA foam on most of my lifts which is available in several colors to  blend with the shoe. I also have a few different densities to lighten the lift. I use my judgement to determine the best material based on the lift elevation and type of shoe. I do a pretty good job blending the lift with the shoe. My talents with your expectations can be another matter. In the end product, I am adding material with different textures to only one of your shoes.