Keeping warm while ice fishing is next to impossible on some days, unless you have a good shelter. Many “pop-up” tent style shelters are available on the market, all of which have hefty price tags, but none equal the comfort of a home-built wooden shelter. The keys to keeping warm on the ice are getting your feet off the ice, getting out of the wind on sunny days, and using a portable heater on cold, windy, overcast days.
Source: Fix.com Blog
At this point, feel free to apply any weather-sealing products and paint you like; the better they are, the longer your lean-to will last. You should also go around all the edges with some silicone caulk and seal up any spots where wind and rain can get in.
This is a fun project that one person can easily do over a weekend. It can function as a lean-to on sunny winter days to help break the wind and get your feet off the ice or as a complete shelter for lousy days. You can customize and modify this design to your liking.