Cut a piece of branch to a 3-5” length, and find a drill bit to bore holes in one of the cut ends.

Bit logs

Make Your Own DIY Lincoln Logs From Scrap Lumber

Use a 3/4-inch dado router bit to cut your notches and use a backing board to prevent blow out. You can go with a traditional look using walnut stain for the logs and red and green for the roof pieces, or pick your own for a custom .