Large scale methanol free protein production in yeast species like Komagataella phaffii is a very important application in the field of industrial biotechnology. Therefore, a good performing and characterized production strain for is an essential requirement. Small scale bioreactor cultivations up to five litres working are commonly used to evaluate a strain and its protein production behaviour prior to more expensive upscaling. Nevertheless, also small bioreactor cultivations in fed batch mode are laborious, time-consuming and rely on expensive equipment, especially if multiple strains need to be evaluated in parallel. To simplify initial cultivations of a new protein production strain we established a simple shake flask system for methanol free expression that simulates bioreactor conditions including a constant slow glycerol feed and online monitoring. Recombinant protein production is driven by the carbon source repressed promoters PDC from K. phaffii. Polymer discs, releasing a constant amount of glycerol assure a feed rate that keeps the promoters de-repressed and active while keeping biomass production low.