any one know how to build a kiln that can heat up to over 2500?

Answer 1

To go over 2500F with electric, you have to get expensive because you are above the temperature range of ordinary materials used for ceramics and glass kilns.
Heating at those temps (but well below 3000F) requires Silicon Carbide heating elements which are relatively low voltage and high amperage which requires heavy duty adjustable transformers to match current flow to changing resistance it temperature. Go to CraftWeb's glass forum (wwwlcraftweb.com) and look at the archives about electric melting.
You will also have to do with higher temperature refractories and you can buy these for more money at refractory suppliers you will find in the Yellow Pages.
One alternative would be to use higher temp materials for the walls, but switch to gas/blown air for heating.
If you want to go over about 2900, you will have to use oxygen with fuel gas, the refractories get very expensive and you still have to rebuild the kiln after a few months. There is a guy who built a glory hole for furnace working Pyrex (borosilicate) who has experience.

Answer 2

build a kiln???
u should probably gfo out and buy one rather than build one