A note from the BBC Press Office sent in the early 1980s to a Doctor Who fan who requested the plans to construct his own Dalek has recently been unearthed by Letters of Note. The BBC did indeed send the plans, along with a warning to the fan (Ronald) that "the constructed Dalek will be used only for personal uses."
In other words, Ronald, please don't use them to invade Earth or film your own rival television series. A little digging around by us revealed that plans to create a Dalek still exist on a somewhat ancient fan site (although we're not sure if they're the BBC ones or not), and we've included them in the gallery below for your enjoyment, along with Ron's letter.
Please note: We don't particularly care what uses you put your constructed Dalek to. (Though if you do make one, send us pics, please!)