Thermoformed polymeric foam articles and methods of forming the same are described. In some embodiments, thermoformed articles are produced from multi-layer foamed sheet where the formed article has a density equal to or less than the precursor multi-layer sheet. One of the layers of the thermoformed article may be a polymer foam layer having a density reduction between 5% and 50% as compared to the solid polymer. Such polymer foam layers can be referred to as “medium density” or “high density” foams. Advantageously, the methods described herein are practical for commercial use and, for example, can be used to produce a variety of thermoformed articles suitable for use in many different applications.