That's way I would suggest making of the masks and then or putting them on a model surface and then airbrushing or putting them on a sheet of clear decal film ( these are offered by most hobby shops ), airbrushing and you have own decals.The last way can be done in a couple of ways.For instance two masks should be prepared , the first one for white numbers ( bigger at about 1-1.5 mm then the red ones ) , the second mask for red numbers.Then the masks for white have to be put on a clear decal sheet and white colour applied.The same way should be done with red ones.And then these numbers should be cut off and put on a model one on one.But in my opinion it would be better to spray the clear decal sheet with a white and when dried the masks for red numbers should be put on the sheet.Then spraying with the red colour.The dried numbers cut off the sheet with scissors or a scalpel with white outline.