  Internships help students connect what they have learned in the classroom to
the real world, and students with access to internships are more likely to
graduate and secure employment. However, many students are unable to find an
internship by the time they graduate. This experience report describes a
program where volunteer software engineers mentor students as they work on
open-source projects in the summer, offered as an alternative to a traditional
internship experience. We catalog the considerations involved in providing an
experience similar to a traditional internship, describe our program's design,
and provide two years' worth of participant evaluations and career outcomes as
a measure of efficacy. The program served mostly undergraduates from non-R1
schools who are underrepresented in technology, and achieved similar
educational outcomes to a traditional internship program. Most promisingly,
mentors were willing to serve as a professional reference for 80% of students
and the number of graduating seniors who secured full-time employment in
technology was 7 points higher than average (despite occurring during the
COVID-19 pandemic).
