Abstract: Portable electronic devices having an outer layer comprising cork. Such portable electronic devices are portable, compact, and relatively lightweight. The outer layer comprising cork provides improvements in functional performance and ergonomic benefits as compared to hand warmers having polymer or metallic outer layers. The portable combined hand warmer and power bank with an outer layer comprising cork exhibits improvements in heat retention, heat distribution, and limited heat transfer to the initial touch. The outer layer comprising cork is comfortable and relatively soft and grippy as compared to the plastic or metallic outer layers of conventional hand warmers. The portable electronic device having the unique outer layer comprising cork also repels and wicks moisture as compared to other hand warmers having plastic and/or metallic outer layers. The outer layer comprising cork can also be relatively anti-microbial and germ resistant.