I'm looking for a sturdy white cake base to support a heavy cake. I used wilton silver cake bases, but I think I need something stronger and in white. Let me know if you have any ideas. Thanks

You can always get some plywood and cover it in white food foil.

When I did a 5 tier last spring I used about 5 wilton boards taped together. I covered them in foil- but you could use white.

I get squares of 1/2" plywood from my local lumberyard for less than $5 then cover them with white freezer paper.

Yep, get yourself to the lumber yard
That way you can make it as big; tall or shape you want it.
Cover it w/self-stick shelf liner.

Diddo! Plywood and a jigsaw are wonderful.