I want to create bunch of maps for a homebrew d&d campaign.

I am a self taught Turbo-cad user (poor mans autocad) and I am very proficient in it so that is where my experience is.

What i want to do is create wall sections, doors, windows, furniture, etc and save them as symbols then piece them together on different layers in Gimp

for example: have a floor layer, then walls, then objects (chairs, chest, etc), then use gimp to add shadow and light effects

In cad programs you can save images as symbols then piece them together, i cant seem to find a tutorial that shows how to do this in gimp, or even if it can be done.

I have tried to save wall sections i have built and then open each image as its own layer, then flaten, but you cant go back and manipulate later (at least i cant at my current skill level in Gimp)

I have played around with maptools, i find it very clunky but it does the job, except i wish to save my maps as png's and use them outside of rpgtools, when i export the resolution is terrible.

will gimp even do what i want it to do