Neoprene, along with 2 x 48W heat cables for the primary mirror and main tube body, and 2 x ~8w heaters for the secondary mirror and eyepieces; 12V PWM controlled (mains power for now, battery later)

NB: this is a prototype design based on reading other peoples ideas, no idea if or how well it will work for avoiding fogging

Waiting for heater components to arrive, for now just the neoprene...