To know, whether a tree at a site is vital in the present and viable in the future is of growing relevance. One parameter that can provide information about the constitution of a tree is its increase in trunk perimeter. This contribution to the topic of forest monitoring, more precisely dendrometry, is motivated from this perspective. Based on market research on existing dendrometers and defined demands of users, a concept for a new dendrometer was developed in several stages, which was implemented and successfully tested as a demonstrator. The idea was to simplify an electronic measurement of tree trunk perimeter growth, and to make it accessible to a wider range of users. As a preliminary result, a graph of the trunk perimeter of a pine tree from values measured hourly over 15 months is presented and, among other things, two dents conspicuous therein are discussed. The documented material can serve as a template or inspiration for context-specific topics.