We used a bandsaw to remove the bulk of the notches for this ladder. The detail and finish work was done with a small adze. Other woods would work including sections of logs.
Ladders, used outdoors, are always on uneven terrain, it seems, and there is considerable danger of falling, dropping and damaging materials, or enduring unreasonable difficulties. So we set out to correct the situation and in the process construct an all-purpose ladder that would meet all of our needs.
Sometimes I spend more time climbing up and down a ladder getting tools than I do working on the job itself. So to keep my tools within easy reach, I attached a plywood tray to the top of the ladder. Several holes are drilled in the tray to accept the tools I use most often.
Ever since man learned to use edged tools he has made ladders or steps, or whatever you may call them, by notching logs.