A Holga camera is modified to imprint metadata in the photographed image; a stencil projection system impresses the date (or other text) onto the film.

Also, a slide viewer was transformed into a perpetual calendar, which can be photographed by most cameras- No costly Holga alterations needed.

External gallery: https://www.lomography.com/homes/jesseengland/photos

Explanatory video:

http://jesseengland.net/files/gimgs/th-25_holga_date_promo.jpg
http://jesseengland.net/files/gimgs/th-25_date_stencil_evolution.jpg
http://jesseengland.net/files/gimgs/th-25_perpetual_calendar_slide_viewer_04.jpg
http://jesseengland.net/files/gimgs/th-25_May 10 2024.jpg
http://jesseengland.net/files/gimgs/th-25_009 June 22 2024 copy.jpg