The gender gap in computing has persisted—and grown—over the past 40 years. One class of solutions offered as a way to close the gap are software and hardware design tools created for girls. This study compares one such construction kit—the Adafruit Flora—to a comparable kit that was not designed with girls in mind—the Arduino Leonardo. Using an experimental design, we found that at the start of the study the girls held largely stereotypical attitudes, and that these attitudes became less stereotyped for the girls in the experimental groups. Furthermore, we found little difference between the two experimental groups, casting doubt on prior claims as to the effectiveness of gendered construction kits on girls’ interest in and attitudes towards computing.