Now, you have the kiln set, but you need to have a source for the light. This will be an emission material. With Cycles, your light source can be any shape:
Press the 3 and 5 keys on the NumPad to get the Right Ortho view.
Press Shift + A and create a UV Sphere from the Mesh menu.
Scale it down so it just fits within the central cavity of the kiln.
In the Materials panel of the Properties window, press the + sign to create a new material. Click on the New button. Name the material Light.
In the Surface subpanel, change the Surface from Diffuse BSDF to Emission. You may have to scroll to the bottom to find it.
Set Strength to 60.
In the Timeline window, select the Current Editor Type button, and choose Node ...
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