Camping Heater.

thingiverse

Uses a 12v 100w PTC heater off of Amazon along with a temperature controller off of Amazon. Total Power consumption is around 8.5A at 12v DC. Total Cost was about 35$ USD for entire build including wires, connectors, plastic cost, and other misc parts.Update: After some use I found that the fan vibrates and does not like to start up when its cold, leading to an unpleasant screeching noise along with the fan blades barley rotating until the heating element warms up the bearing enough. I replaced the fan for one that is a little quieter and has dual ball bearings instead of one solid brass bearing.Update 2: Been using this heater every day for about 8 hours a day for the past month. Its worked reliably without any issues whatsoever. After calculating out the price of energy this heater consumes, I found out that it uses about $3.2 USD each month, or about $38.4 USD a year.PTC Heater: https://www.amazon.com/gp/product/B08YX4ZSFX/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1Temperature Control unit: https://www.amazon.com/gp/product/B07K7KJ788/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1