What I did was choose a box mold that I wanted. My husband took those measurements and went from there. When we eyeballed the rough wood and held together a makeshift box I felt my bars would be skimpy so we expanded it a bit.
My bars measure - 3.25 x 2.5 and I cut them 1 inch thick. My shortest box is 24 inches long.
So for that box the interior measures 3.25 x 2.5 x 24.
We used 1 x 4's to build the boxes. All untreated lumber. You will get oils on the wood. Don't worry about it! Do not wash the boxes. Water is a big no-no. The oil actually begins to soak into the wood and protects the boxes. My boxes get better the more I use them.
My bars measure - 3.25 x 2.5 and I cut them 1 inch thick. My shortest box is 24 inches long.
So for that box the interior measures 3.25 x 2.5 x 24.
We used 1 x 4's to build the boxes. All untreated lumber. You will get oils on the wood. Don't worry about it! Do not wash the boxes. Water is a big no-no. The oil actually begins to soak into the wood and protects the boxes. My boxes get better the more I use them.