This is a simple tool to turn help you make a 3D model out of a planimetry / map.
Instructions: To change planimetry, use the controls on the left. Then:
Define a scale by picking 1 meter of length on the planimetry
Adjust the thickness of the wall/door/window you want to add
Select the type of entity you want to build from the list (wall, door or window)
Draw the entity on the map by clicking the starting and ending point of every entity
Iterate this for everything you want to draw
Go see the generated 3D model in the viewer by clicking the 'generate' button
The 3D model will open in a new tab: the link can be saved for later as it stores the model information. From the viewer you can also download the 3D model to use it in more advanced editors.
Planimetry: