My husband and father-in-law built this crib over many weekends. They decided against using pine since it is soft. Instead they used maple and the materials cost far more than the $50-100 estimate. The finished project is beautiful and is lovingly referred to as the bomb shelter because it is so sturdy and heavy.
They made it so the mattress could be raised and lowered as well as easily converted into a toddler bed. They used the crib mattress as a starting point to adjust the plans to ensure there would be no gaps between the sides of the crib and the mattress.
They used a router to put a dado at the top and bottom of the sides so the slats fit into the slot instead of just butting against the top of the rail in order to minimize the number of nail holes and create a nicer fit. They used one solid piece of maple plywood at the ends of the crib because there is a lot of temperature variation where we live resulting in a lot of expansion and contraction and they wanted to make sure that didn't cause any gaps.