Hi Tm,
all 7 of the ESpot gobos are replaceable.
So when you order your gobos make sure you specify the size.
26.9mmOD x 24mm viewing image
The manual states a max thickness of 1mm can be made.
this means that you can use metal or Glass gobos without a problem. however when you use glass you will be limited to 1 color. when you start adding colors the gobo gets thicker, unless you use www.gobostogo.com they are the only gobo manufactuer that I know that can make multi color glass gobos into a 1mm thick gobo.
Now a trick with the eSpot you can try, since its only using an led source, you can print a gobo on transperancy film.
Try and print it 26.9mm OD by 24mm viewing and it will be the least expensive gobo you can make.
the transperancy could last 3 days or may work well for a month, then you have to print new ones.
Give it a shot.
Best regards,