The lack of gender diversity in the STEM is an ongoing issue, as studies show that girls are often discouraged from pursuing careers in this field due to societal stereotypes and a lack of role models. This paper presents the consecutive multi-day girls' project days, which are realized at the Technical University of Darmstadt, Germany and introduce up to 60 girls aged 10 to 16 each year to engineering and the STEM field in general. The three-day hands-on labs provide girls with the opportunity to explore their interests, develop their skills and build confidence in their abilities. Due to the consecutive approach of the girls' project days, the girls can attend a new workshop every one to two years. The evaluation of participants' feedback and an evaluation in form of questionnaires show that attending the project days has a positive impact on the girls attitude towards pursuing a degree or job in engineering.