| <<< Texture support for import would be also a nice 
feuture to have, but for a free app i can't complain. 
@Stefan 
Hello 
In Magica Voxel you can Import an Image PNG 126*126  in Edit Mode so 126*126*1 inside MagicaVoxel  
(only Drag&Drop : menu Import don't yet existing) 
increase after import the general matrix following that you want 
Larger scene area: (-1024, +1024) 
Maximum matrix is : 512x512x512, 1024x512x256 or 1024x1024x128
 
As you can make one Multiple Drag&Drop image(s) you can have the same than above! ;) 
Just find something who trim your original image in step 126*126 pixels on some png files ;)
 
After import image you can of course make some landform with some extrude following matrix aceptable
 
The OBJ export will report all this! ;) 
Here after some extrude and increased the 126*126*1 matrix
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