Where do you get planks for your den?

You get them from lilycove department store on the top level when the sale is on I think there called wooden plank

When the Lilycove Department Store announces a clearout sale, go to the top level of the store and talk to the vendor there. He can sell you a Solid Board for P$3000.

You get them from Lillycove shopping mall when a slae is on. To find out when the sale is on keep looking at your TV and it will tell you.

Look at the TV in houses... When it says it's sale at the Lilycove Big mart then you must go to the top and there will be a women who sales a solid board , buy it.

This is to Smithyere
You asked were to get planks for your den.the answer is lilycove department store.
When they have their sale on go to the rooftop and talk to the guy at the top of the screen to the left of the vending machines.He will offer you a heap of rare stuff for your secret base/den including planks.

I'm guessing that you're asking where you can get a Solid Board for your Secret Base. Well, check TV's and when you see a commercial that says the Lilycove Department Store is having a Clear-Out Sale, keep checking TV's and when it says that it's today, go to the Department store, on the top floor, and there will be a person sitting up there. You can buy stuff like:
Slide
Tire
Mud Ball
Stand
Snorlax Doll (big doll)
Rhydon Doll (big doll)
Breakable Door
Solid Board
TV
Cute TV (?)
Round TV

I think there's more, but you get it; a TON of cool items. Just remember to save up your money, because it's only for one day, until it goes away, for awhile.

From people who sell decorations for your secret base. Also, in special events, a man at the very top of the Lilycove Dept. Store appears and sells you decorations only he sells.

You get them from the big sale at lilycove department store.At the top level, can't get there by elevator, you got to use the stairs.