I managed to drag my 40106B frequency doubler circuit into your 555 50% Duty Cycle Output.asc.
I like the way LTspice re-numbers the passive components.
Like Alec_t said "duplicated names spell disaster". I had 2 "OUT's" and LTspice spat the dummy.
Got that sorted and it appears to work fine.
I have wired the output of your circuit directly into the 40106b circuit, I am not sure if this is the best way.
Should it be via a capacitor or a resistor?
What software would you recommend to go from LTspice.asc to board layout or even to PCB?
When I make the transition manually my boards are large mainly due to idiot proofing them to protect me from me.
Depends.
The easiest is to use layout software that goes directly to board fabrication, such as from ExpressPCB or PCB123.
But the boards are somewhat more expensive then using stand-along layout software, such as Eagle or Diptrace, and then sending the fab file to a PCB vendor, however the learning curve is steeper for that approach.
So it's a tradeoff between easy and cheap, take you pick.