Systematically-processed empirical knowledge and well-thought-out moulded part design and process control constitute the key to the successful production of moulded parts by gas-assist injection moulding. Prior to implementing the part, it makes sense to conduct a suitability test: which geometric requirements does a moulded part have to fulfil for GAIM? The answer is obtained from a detailed catalogue of criteria, as is shown here in the first part of a three-part series on this subject.