(Adan)  One of our early prototypes was recently back out on the table, and we all had a good time looking at it.  It's a complicated one, lemme tell ya: building blocks!
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This prototyped set is made of pieces of maple, square in section, ranging in size from 1.25"x1.25"x1.25" up to 1.25"x1.25"x7.5".  
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These were a very early project.  We've gotten a LOT more tools and skills since then.  A contemporary set would look much nicer, I feel sure.
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But hey, they're building blocks!  They don't have to be fancy to be a lot of fun.  I enjoyed myself greatly just building this reindeer.  Or spaceship.  I forget what it was, but it was absolutely perfect.
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If we were to make another set like this I would probably want them to be made of beech.  I might also consider tweaking the common dimension up to 1.375", which is apparently a standard (??) building block factor.  What do you think?  Oh, and how should they be packaged?