Here is my first sketch for a two-hand-operated chest mounted lance thrower.
The design is based on the pencil launcher of course, but with the power of both arms, this will be one terrifying weapon.
I hope that I can launch the heavy aluminum tubes with steel spikes (45 cm total length, = 18") at 50 m/s (164 fps). That would be 143 Joules = 105 ft.lb of energy, with tremendous penetration potential.
My goal is to make this the world's most powerful muscle-operated, one man portable repeating weapon!