Busy with tracks

My three-and-a-half-year-old would be content to spend ALL DAY every day just playing with his trains and tracks on our living room floor.  We've had many sick days (and many rainy days) over the past couple of months when I have let him do just that.  Today, though, while he was out on an adventure with his daddy, and the smaller munchkin was napping, I decided to test my skills at using train tracks to create his name.  I am pretty impressed with the results.  He was thrilled!

It got me thinking about my son and what he is interested in and not interested in.  He is mostly content to play with trains and also learn about anything with wheels or anything related to infrastructure or construction.  He could watch informational movies about road building, heavy machinery and most recently - home construction for hours on end.  (The Mighty Machines series is his all-time favorite.)  However, try to get him to sit down and learn about the ABCs and he is completely uninterested.  He recognizes quite a few letters, but it's just not important to him at the moment.  I'm not hugely worried about this, it's actually more of an observation than anything else.  I believe very strongly that young children should be left to play/create/imagine to their heart's content and that letters and numbers will come when they are older.  They have their whole lives to fill their heads with words and numbers but the years full of imagination and wonder are so brief.
Anyway, I was thinking that using the train tracks, I might be able to multitask.  Why not use train tracks to build letter shapes?  Boys tend to like to move more than girls and often have less-developed fine motor skills at this age.  I found when tutoring a little boy many years ago that we had the most success with writing when we wrote huge letters on concrete with sidewalk chalk.  I am curious to see if running trains along letter-shaped train tracks could actually help my son learn letter-writing skills?  This could also be used for shapes, numbers or even patterns.  Obviously connecting all the letters like I did takes a lot of fancy connections - we have a local toy store that sells them individually and so every time we go there, I grab just one more since I'm a mom who loves the toys as much as the kids.  Simple shapes and patterns, though, could be created with fairly standard pieces (circles, ovals, zig-zags, waves).  Big individual letters could also be done without very many non-standard pieces too.  Even drawing big letter train-tracks with markers on butcher paper or freezer paper could provide lots of entertainment.
I am going to further investigate this...I like a track-building challenge.  Would you all hate me to learn that the Nathan track only took me about 20 minutes to create? I think I have a freakish talent for these sorts of things.
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Woohoo!  This idea was featured on OHDEEDOH!  Happy building, everyone!