Ha! Regarding construction and tuning- the strings go through the drumhead and are attached to a reinforcing string bar on the back (like a real harp)Drumhead is attached to circular frame with banjo pins (!) then the whole thing is fitted on a 2 X6 which is embedded in the hollowed out pumpkin.The superstructure is attached to the pumpkin with bunjee cords. Strings are actual harp strings, tuning pins are threaded piano pins.
To be truthful, the pumpkin itself has zero resonance, the walls being about 3-4 inches thick and fleshy.
Tends to play in squash-flat...a more or less (diabolic) diatonic.
It has 19 strings -I tuned it so that "do" (doh!) is the fifth string from the bottom to maximize range for both hands.
Big hits were Ash Grove, Fanny Poer( with moderations), Heart and Soul, Ode to Joy, Simple Gifts, Merrily kiss the Quaker (first two parts), Fairy Reel, March of the King of Laois. The challenge is the range of the tune- ancient harp tunes seem to fit well

There seem to be giant pumpkin growers everywhere- ask your local farmers market?Or grow your own!Several websites available
Remember that this is ephemeral art...We will be having pumpkin influenced meals for awhile, lotsa pie

Cheers all- Julia

PS If you are interested in other types of gourd-o-chords, check out the African Kora