The Leil Celto M is a three-person outdoor sauna that combines a compact footprint with more room for shared sauna sessions. Its clean design and large glass surfaces create a bright, open interior that stays connected to the surrounding outdoor space. The Celto M uses substantial Cross-Laminated Timber (CLT) panels for the walls, ceiling, and floor. These structural panels are approximately 2.36 inches thick. A self-adhesive EPDM covering protects the roof for outdoor installation.  Inside, the sauna features two-level seating with an upper bench approximately 24 inches deep. A lower seating section measures approximately 16 inches deep and 19 inches high. The layout provides flexible seating while making efficient use of the interior.  The Celto M uses Aspen for its benches and wide single-board backrest. Integrated LED strips beneath the backrest provide soft interior lighting. Tempered bronze glass and a glass door give the sauna its modern, open appearance. Four ventilation openings help support airflow during and after sauna sessions. The Celto M is also designed as a DIY kit for straightforward installation.