It may be a bit late in the season for this how-to, but we may still have a few more weeks of boots and gloves, and you will likely want to give yours a good drying before storing them away, so maybe it is more timely than I think.
Constructed of 1/2” PVC pipe, T-fittings, and caps. I find this diameter pipe provides plenty of support; going with a heavier pipe would likely restrict circulation and reduce air exchange (stagnation of moist air is what fosters fermentation and the growth of mold and bacteria that results in stinky bootie syndrome). The fittings are pretty tight as-is, but I take the time to use PVC primer and cement to fix each joint in place and make them air-tight (more on that below).
I will spare you the detailed measurements as your needs will vary based on hand/shoe size. You may want to consider making it so that it fits inside a plastic bin so you can relocate the entire setup while still dripping wet.
Finally, if you really want to soup it up, tap a brass hose barb (this one is a Watts 1/8” ID x ¼ in MIP; part number LFA-85, available at Home Depot) in the center of the rack, drill one hole in the end of each pipe ending inside the boots and gloves (you may be tempted to go crazy with the drill and make each pipe look like a Wiffle Ball, but that would actually reduce the airflow to the toe and fingertip areas; one ¼” hole as high up on each pipe as possible will maximize the flow from fingertip/toe to cuff). Finally, hook an aquarium pump up to pressurize the system and get some air flowing through the system. The airflow does not have to be forceful; just a little bit of flow will carry dampness out of the wet items.
Finally, I sometimes get asked for advice on how to de-funk boots and gloves. For the most part I just keep up with rinsing with fresh water and drying them completely after every use, but for best de-stinking results, you can wash them in a rubber-safe soap; there are a number of commercially-available wetsuit shampoos, but when the smell starts to get bad I add a little Simple Green in a bucket of warm (not hot as it can damage the rubber and adhesives) water, soak them for a bit, rinse generously with cold water, and dry them out using this pressurized drying rack.