Howdy! Changing the gobos in the SolaFrame Theatre is pretty simple. You will just push down on the gobo and slide the holder out. Once the holder is out, you will need to remove the tension spring holding the gobo in. Just be sure that the black painted side is placed upwards and shiny side is towards the LED engine. We use Aluminum and Borofloat glass in our gobos. You can use steel gobos but one side will need to be coated with a high temperature paint. You can find the dimensions on the technical data sheet at: https://www.highend.com/documentation/SolaFrame Theatre/SolaFrame-Theatre-TDS.pdfLet us know if you have any other questions!