Introduction: Pinewood Derby Car Inspired by LEGO Ninjago

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Our annual Cub Scout Pinewood Derby (http://en.wikipedia.org/wiki/Pinewood_derby) was a chance for my six-year-old to combine two of his favorite things:  making things and LEGO, in particular the story-based world of LEGO Ninjago: Masters of Spinjitzu (http://ninjago.lego.com/en-us/Default.aspx).  

What follows is the story of how we built our car, tricked it out with LEGO Ninjago gear and some cool stenciling, and had a blast doing it all together as father and son.  Not that Lasha, the evil Venomari tribe scout, will be able to escape Cole, Zane, Jay or Kai, but we've certainly given him a fighting chance.

Full disclosure:  I'm by no means a skilled carpenter or brilliant artist, so everything you read and see here can be done by anyone with access to some basic woodworking tools and the listed supplies, which aside from the LEGO pieces can be found lying around the house and/or at any hardware store.  

With that in mind, let's dive in...

Step 1: Getting Started - Conceptual Design and Supplies (including LEGO Pieces)

The first step was to do some conceptual sketches to figure out what exactly we wanted to do with our block of wood.  A six-year-old has lots of ideas, not all of which are technically/financially feasible and, even when they are, can be a bit more time consuming than dad has in mind.  We discussed a number of potential plans though and finally sketched out the ideas attached below.  

Our inspiration was two particular LEGO Ninjago toys that my son loves:  the Fangpyre Truck Ambush (http://shop.lego.com/en-US/Fangpyre-Truck-Ambush-9445) and Lasha's Bite Cycle (http://shop.lego.com/en-US/Lasha-s-Bite-Cycle-9447).  For the uninitiated, LEGO Ninjago: Masters of Spinjitzu is a world of ninjas with mystical powers, talking snakes and dragons, and the classic showdown between good and evil.  The toys themselves go along with a cartoon show that features great story lines and epic fight sequences.  

Our plan was to have our car be the same lime green as the Fangpyre vehicles--those are the bad guys--and then reuse the tail and cockpit from those same kits to give it that LEGO effect.  And of course we wanted to make the front look like a snake's head.  I've attached our scribblings as an example, as well as an action shot of the real Fangpyre Truck.

In terms of supplies, the standard derby car kit comes with the block of pine, four wheels, four nails (to secure the wheels) and some numbered stickers.  We supplemented our supplies with the following:

- One (1) Cockpit Window from the Fangpyre Truck Ambush
- One (1) Whipping Tail from Lasha's Bit Cycle (Fangpyre would work but its a bit larger and heavier)
- One (1) can of lime green spray paint
- Two (2) red rubber screw caps (for the eyes)
- One (1) think tip Sharpie (for the stenciling)  
- One (1) 1x2 thin LEGO
- One (1) 2x2 thin LEGO

The last two are CRITICAL if you want to recover the cockpit window and tail from your Derby Car, because you can just glue them on and then attach the more complex pieces.  Now onto the construction phase...

Step 2: Basic Construction - Sawing, Sanding, Routing and Painting

Nothing extraordinary about this part.  The wee man and I spent a Saturday afternoon together.  I won't bore you with detailed play-by-play, other than to note the following:

- Definitely work out the cut patterns on paper before you go near a bandsaw or sander.  We went through several iterations of the profile, overhead and front views before we aligned on the overall aesthetics (see photo for profile cut pattern).

- If you use an electric sander, beware that material disappears VERY quickly.  Less is more--you can always take away, but its impossible to put back.

- If you have access to a table-top router, definitely make an underside cut as part of your pre-paint process.  That way you can add bits of metal at the official weigh-in.  Doing it once the body is painted and the wheels are attached can be tricky.  I recommend 1.5" wide and maybe 3-4" long.  Our scout pack had a wood template to sit on top of a Ryobi intermediate router, made the whole process a snap (see photo for underside image).

- Spray paint is easiest, do it outdoors, and remember to weight the edges of your paint tarp so that little gust of wind doesn't knock everything over (see photo for our impromptu paint stand).  

With our green body in hand, it was on to the flair...

Step 3: The Details - Stenciling the Snakehead and Adding Eyes, Fangs and a Forked Tongue (and of Course Stickers)

The key during this phase was the stenciling.  I practiced on paper before I drew it on the derby car.  

One thing I didn't account for was how the wheels would cover part of the sides, but it ended up looking fine.  You may want to check out your wheel placement before drawing though.

Beyond the stenciling, it was all about the small touches.  We used red rubber caps for the eyes, I just clipped off the rounded ends.  For fangs, we had some white card stock lying around, but cardboard painted white would work just as well.  Red felt did the job for the forked tongue--a must for any self-respecting snake.   Then we added a few Ninjago stickers so there wouldn't be any mistaking the origins of our creation.

All that was left after that was the wheels and our LEGO accessories...

Step 4: The Final Touches - Attaching Wheels and LEGO Pieces

For the wheels, I drilled my own holes slightly aft of the default ridge cut into the block.  Some other dads told me the weight was better distributed that way.  The wee man then hammered in the wheels using the provided nails.  

With the wheels attached, I then glued on a 2x2 thin LEGO to attached the Cockpit Window and a 2x3 thin LEGO to attach the Whipping Tail.  That way our Ninjago components could go back to their original homes post-race.

Walking into the weigh-in, we got plenty of attention from the other boys.  More importantly, we ended up adding a few tenths of an ounce to reach max weight, so the router definitely came in handy (see photo).  

We went back and forth a few times to the table with the metal bits and glue gun to make weight.  Finally, our car was approved for the race--we were within 2/100ths of an ounce--and was placed in "The Box" with the other cars.  Needless to say, we stood out a bit (see photo).

As we walked out, the anticipation was already building for race night...

Step 5: The Derby!!

I hadn't been to a Pinewood Derby in more than three decades, so I wasn't sure what to expect.

We checked the schedule when we arrived and learned that the wee man was in the first heat for his Den.  Six cars raced at a time and he finished 4th in both heats.  Sadly that wasn't enough to advance to the next round.  Of course, we didn't go in for the whole sanding down the nails or applying graphite to the axles--our hope was that the wee man's car would be recognized for other reasons.  

As the night wore on, we cheered our fellow Den members as they competed against the rest of the Pack.  We also checked out all the other cars.  With about 30 minutes to go in the evening though, our Scoutmaster came over and asked my son to come with him.  They walked up to the stage together and the Scoutmaster proceeded to announce that the judges had awarded the coveted "Most Creative" award to the wee man's car.  We cheered, he beamed.      

My parting advice for dads and their Cub Scouts:  go for aesthetics over speed...and grab some LEGOs.