Great idea Kataki. It's actually a very easy to change.
Both this are taken in the same game. First is the Observation periscope and the 2nd is the Attack Periscope. Doesn't really fit together, but you get the point.
Observation Periscope(Graphic:OAK) - Attack Periscope(Graphic: 2RTR)
Observations Periscope Code:
[G2B I136]
Name=BackgroundWithWhole
Type=1030;Static bmp
ItemID=0x2B000001
ParentID=0x2B000000
Pos=0,0,1024,768
Zone= 0 768 1024 768 5 1 0x2B000000 0.5 -0.5 0x2B000001 -0.5 0.5 0 0
Color=0xFFFFFFFF
Materials=1
Display=2;Linear
Mat 0=data/menu/gui/layout/
periscope_mask_1024.tga
Crop 0=0,0.125,1,0.75
MatFlags=0x9
TexFmt=0x0
Change to whatever graphic you'd like.
Attack Periscope Code:
[G26 I137]
Name=BackgroundWithWhole
Type=1030;Static bmp
ItemID=0x26000001
ParentID=0x26000000
Pos=0,0,1024,768
Zone= 0 768 1024 768 5 1 0x26000000 0.5 -0.5 0x26000001 -0.5 0.5 0 0
Color=0xFFFFFFFF
Materials=1
Display=2;Linear
Mat 0=data/menu/gui/layout/
periscope_mask_1024.tga
Crop 0=0,0.125,1,0.75
MatFlags=0x9
TexFmt=0x0
Change to whatever graphic you'd like.
As default both use the same .dds file(
periscope_mask_1024.dds), changing this single line for either obs scope or attack scope will change graphic for that periscope.