I am a bit lost. OpenStreetMap was suggested to me as a custom mapping tool.
I think my issue is a bit strange in that I want a map but not of a place.
I want to map out a storage space of a factory. I realize that I will likely lose GPS functionality with this but one problem at a time…
the storage facility is a simple grid layout. Columns A to GG and rows 1 to 17
so like this
A B C D E F G H I J K L M N … AA BB CC DD EE FF GG
and items will be stored in like location A1 can contain 12 items
location B14 can contain 4 items D 12 can have nothing…
OpenStreetMap is simply a database for geographic data for the world (http://wiki.openstreetmap.org/wiki/Main_Page). This data can be used for a lot of applications, e.g. to generate maps for websites or navigation systems. Some application uses OSM-Data as a general background-information and add specific data (which are not part of OSM) as an overlay.
So if you need (realworld) geodata for your project you might be at the right place.
Reading your specific request, which only concerns a single design project likely involving some private factory building off limits and of little interest to the general OpenStreetMap users, I really think you should be looking at CAD (Computer Aided Design) software.
Although there are some nice OpenStreetMap editors, they were not designed with this kind of use in mind, and at best allow you a clunky way to accomplish it.
In addition, OpenStreetMap is not a private mapping tool. Any data you enter, will be shared with all other users through a global database. This may not be what you want, nor even what you are allowed to do by your employer.
Alternatively, if you can’t afford a decent CAD package, have a look at QGIS (http://www.qgis.org). It is a free GIS (Geographical Information System), that at least allows you easy personal project creation, and printing of your map or design.