The stove in my kitchen was being replaced in the morning, and inspired my idea.  I wanted to make an oven knob that would also be a timer.  The knob would have LEDs embedded in it that light up to indicate the time elapsed.  A switch would reset the timer.  For simplicity, the timer will light up an additional LED every 10 minutes.

I created a mold using vacuum forming.  Some wrinkles formed in the plastic sheet, but they were narrow and Claire suggested putting tape over it before molding instead of forming a new sheet.

I molded using the VytaFlex 60 since I wanted the knob to be reasonably hard.  I put in some blue dye to make it prettier.  Some of the polymer spilled over during the process and was wiped using a paper towel.

The cast knob was extracted using a drill bit (since I couldn't find an exacto knife).  The spill caused a thin film to attach to the wires and around the rim of the knob that had to be cut off.  The tape also left some residue that needed to be washed off.

The timer code loops forever at a constant rate.  It was experimentally determined that a second is approximately 10 ticks.  While this is likely not exact, the difference is not significant over the 1 hour timer period.  Each second, the counter is incremented.  Depending on the value of the counter, 1 - 3 LEDs are lighted to indicate 20 minutes, 40 minutes and 1 hour.  A button press will reset the counter. If the counter hits the one hour value, it is frozen so the user will realize it before resetting.

to TimerBlah
make "Counter 0
make "Second 10
make "Mult 1200
forever [
make "Counter :Counter + 1
if :Counter > :Mult * 10 [
make "Counter :Mult * 10
]
wait :Second
if :Counter > 0 and :Counter < :Mult * 1 [
a, off
b, off
c, off
]
if :Counter > :Mult * 1 and :Counter < :Mult * 2 [
a, on
b, off
c, off
]
if :Counter > :Mult * 2 and :Counter < :Mult * 3 [
a, on
b, on
c, off
]
if :Counter > :Mult * 3 and :Counter < :Mult * 4 [
a, on
b, on
c, on
]
if sensor1 = 0 [
make "Counter 0
]
]
end