Nothing new and has probably been done before but here's some simple 128^2 dev textures I made because every custom 'dev' pack always just used the smaller grid size ones instead. The textures just remove the visible text on the texture (e.g. wall 128x128), whilst keeping the same colours as best as I could (importing from gfcscape slightly adjusted the tone which i corrected for).
It includes the standard red/blue/orange/grey and a few of the shades of white (reflectivity x) plus some extra variations I made e.g. black, green etc.
https://www.dropbox.com/s/bzor6ztjebtcxpj/pantsdev.zip?dl=0'
Free to use if you put an exile style pair of pants in your maps
or make something explode in the map