Well, I thought that I'd just drop a picture of the Tardis Keys I've collected and used in my photos and cos-play costumes and such. A few of these i have made, one was customized by me, and the rest are actual licensed collectibles.
From left to right, top row: An old six pin Yale key that I had filed out nice and smooth front and back, same with the second key which is a more standard 5 pin type that I had cut to match the John Pertwee key from the episode Spearhead From Space which was Johns first episode as the Doctor. I had used screen caps for comparison. Next key is an ERA key based on the 2005-present series, and the last is a brass key that I had smoothed out, then textured with a fine wire brush wheel and then aged with a hydrochloric acid based solution.
Second Row: A solid cast aluminum key that I had customized with a set of precision files and then made a new chain loop for out of a strip of aluminum, then strung on an antique snake chain. Next, is a John Pertwee era key that was molded from a screen used prop. This key was the first spade shaped key in the Doctor Who series and was featured in episodes such as Planet of the Spiders. Next is a Sylvester McCoy key as seen in the episode Ghostlight that I had purchased from ebay and then had aged and blackened with the same hydrochloric acid solution I had used on the brass key. The last two are official releases based off the spade shaped Tardis key. One is limited to 3,000 pieces and then the original mold was destroyed. It is pewter and therefore rather soft and easy to scratch. The Last is made of Pewter as well, but seems to be of a higher tin and silver content and is much harder and darker a metal, it is also the most readily available of the officially licensed Tardis Key Replicas.