The importance of Modelling Method Engineering is equally rising with the importance of domain specific modelling methods and individual modelling approaches. In order to capture the most relevant semantic primitives that address domain specifics needs, it is necessary to involve both, method engineers as well as domain experts. Due to complexity of conceptualization of a modelling method and development of regarding modelling tool, there is a need of a guideline and corresponding tools supporting actors with different background along this complex process. Based on practical experience in business, more than twenty EU projects and other research initiatives, this paper introduces a toolbox to support the conceptualization of a modelling method. The realized toolbox is introduced and evaluated by two EU-funded research projects in the domain of e-learning and cloud computing as well as additionally by an in-house development project in the area of decision modelling extensions. The paper discusses the evaluation results and derived outlooks.