For more information, see a very similar design here by Zookeeper15133 at

Slots are cut all at one time to make sure they all line up.

After the saw cut, use a wood chisel to remove the slot.

Setting up the apex.

Gusset plate screwed in place

Marking the angle for cutting.

End section

Apex ready to receive the ridge piece

Apex showing gusset plate

Basic framework

Building a Chicken Ark – Part 2