Can I add new items to the toolbox? Preferably with the ability to completely control length and width.

I work at a company doing drawings of custom crates to aid the guys who assemble them in keeping track of what board of what length goes where. Right now I have various boards set up with configurations that control the length down to the nearest quarter inch- if I want finer control, I have to add

This works ok, but I can't help but think there must be a way to add a simple item like a 2x4 to the toolbox and be able to drag it over and make it whatever length I want, instead of having to make a new configuration for each length. Or if I could drag over a piece of plywood and adjust the length and width to whatever I want. Does anyone know a way to add such items to the toolbox?  Or any other way to do this that would be more efficient than the way I have been doing it?