I have a light box that was made to suit the Tak FSQ106 though it will suit any refractor that has a dew shield diameter of 144mm or there about. I've measured the inside diameter of the front of the light box and it is 146mm. It has a dimmer to allow for illumination adjustment. These light boxes are a great way to take nice even flats for your image processing work flow.
Price $195.00 plus postage. (I will accept reasonable offers
).