This is an isometric drawing homebrew application on the NDS, which has several colors to choose from.
Rename the extension nnn to nds to be functional.
With this application you can draw simple pieces (that have all the planes parallel to the projection planes) in isometric.
Click on the part of the isometric network so that the cell is filled with the selected color.
Stylus - Change color, Draw
Start - Clear all
Tested on NDSTT/Top Toy DS (unofficial firmware 1.17a07).