FPS Creator, Skies For FPS Creator and the Advanced Terrain demo all have the skybox model. You haven’t detailed the problem you’re having, it may not be with your model. If you you’re getting seems in the skybox, you need to set your texture mode to clamping. Anyway, pulled this code off my flash drive. Demo of Rudolpho’s method.
load image "sky_B.png", 1
load image "sky_D.png", 2
load image "sky_F.png", 3
load image "sky_L.png", 4
load image "sky_R.png", 5
load image "sky_U.png", 6
load image "grass.png", 7
sync on
sync rate 60
backdrop on
autocam off
position camera 0, 30, 0
make object plane 1, 10, 10, 1
make mesh from object 1, 1
offset limb 1, 0, 0, 0, 5
texture limb 1, 0, 1
add limb 1, 1, 1
rotate limb 1, 1, 0, 90, 0
offset limb 1, 1, 5, 0, 0
texture limb 1, 1, 5
add limb 1, 2, 1
rotate limb 1, 2, 0, -90, 0
offset limb 1, 2, -5, 0, 0
texture limb 1, 2, 4
add limb 1, 3, 1
rotate limb 1, 3, -90, 0, 0
offset limb 1, 3, 0, 5, 0
texture limb 1, 3, 6
add limb 1, 4, 1
rotate limb 1, 4, 90, 0, 0
offset limb 1, 4, 0, -5, 0
texture limb 1, 4, 2
add limb 1, 5, 1
rotate limb 1, 5, 0, 180, 0
offset limb 1, 5, 0, 0, -5
texture limb 1, 5, 3
set object collision off 1
set object texture 1, 2, 0
set object light 1, 0
set object cull 1, 1
set object fog 1, 0
disable object zwrite 1
make object 2, 1, 7
delete mesh 1
rotate object 2, 90, 0, 0
scale object 2, 10000, 10000, 10000
scale object texture 2, 5, 5
set object cull 2, 1
set directional light 0, -0.768221, -0.640184, 0.0
do
set cursor 0, 0
print "FPS: ";screen fps()
control camera using arrowkeys 0, 1, 2
position object 1, camera position x(), camera position y(), camera position z()
sync
loop
