I am planning to make a pumpkin cake and I thought be cool to to illuminate the inside of it , like lighted carved pumpkins. any suggestion how to do it? Appreciate any help

Use two bundt cakes. Carve, frost, and place battery LED's on the inside.

Thanks Matt, I don't want to just stick the lights in the cake. I want to do it in a way that the front part where the eyes and mouth is , to be hollowed but I don't know how to go about that and how to support the cake in the front.

Chill the two bundt cakes separately overnight.

As Matt suggested, you carve out the middle. I would hollow out more cake from where the face will be. I would then plaster it well with melted chocolate on the inside so it will be fairly rigid.

I would brush more chocolate on the thick parts where the eyes and mouth have been carved out, just to make it as stable as possible. Chill again before adding fondant.

In theory I suppose you could hollow out a chiled cake, on the inside, but just enough to insert one of those plastic christmas ornaments, that you can get to fill and decorate in craft shops. Usually you can get those in different sizes, plop LEDs in that and insert into cake. When you then out the second cake on that, the ornament should be stable enough to hold up the cake, sort of like an inside (round) dowel and you won't have to worry about the cake collapsing on itself

Like this one
http://www.amazon.com/dp/B000LM65Q0/?tag=cakecentral-20+christmas+ornament

One of my friends did a pumpkin cake that had a cake in the back half and the front made out of gumpaste. The front was basically a shell, if I remember correctly, so she could put lights inside and it looked like a real carved-out pumpkin. Best pumpkin cake I've ever seen http://www.welldressedcakes.com/index2.php?v=v1 It's in the carved cake gallery

Thanks everyone for all your suggestions and help