How to make big prims?

Im in need of a panel from 20 x 16 x 1. How can I make a panel like that?
It would save me so much prims.

Hope someone knows.

you can't, not any more, there was an exploit in the client maybe a year ago that allowed people to, and they have made hundreds of huge prims, and these should be free, search for "freebee cave", it's mine, and I have a few hunred boxes up, and I do have mega prims in a few, and they are free, and full perms. And remember you can cut and hollow, and change prim types with mega prims. so say you have a 40m sized one, if you cut it to 75% it will be 20m, and that sort

There have been a couple of periods when a glitch in the code allowd the creation of megaprims. Both been closed off now, but the prims created are still there to be used.

Look on XstreetSL for a thing called a SALT HUD. It finds megaprims and delivers them to you in any size that they're available. Saves having huindreds of them in your inventory.

Thanks for your help

What Wulfric said. That's the best way to get megaprims.

The NCI freebies walls have a lot of megaprims as well.