@RichardOWhy go through such a punishing exercise? You can use Diptrace's free edition to create a four-layer board, and have it manufactured and assembled at Macrofab for <$100. Or have a PCB board house manufacture 4-boards for you for <$50 and assemble the parts yourself.

Status: I have about 1/2 of the parts tentatively placed and about 1/3 of the traces crudely routed. Of course these are the low hanging fruit.

In answer to your questions:

#1 I have more time than money.
#2 I'm cheap.
#3 I can etch my own boards for a couple of dollars.
#4 I have pretty much blown my budget for the pieces-parts that go on the PCB.
#5 I am going to put parts on both sides of the board to keep the layout compact anyway.
#6 I can have the boards the same day I have the layout done. Even these 2-layer boards take 2 days:
http://www.4pcb.com/pcb-prototype-2-4-layer-boards-specials.html
Sneaks up on $100 when shipping is included. Less If I ride my bicycle to pick them up.
#7 Really cheap 2-layer boards can take weeks:
https://www.pcbway.com/
is about $26 for 10 boards
#8 Four-layer boards are much more expensive:
https://www.pcbway.com/
is about $71 for 10 boards
#9 I will likely need hidden vias for other hobby projects so this is a test case.
#10 See #1 and #2.


edit: Finished premature post.

 

https://www.pcbway.com/
is about $26 for 10 boards
#8 Four-layer boards are much more expensive:
https://www.pcbway.com/
is about $71 for 10 boards.

Ooooo! This is my first time seeing this - I may have to try them next time - last project board I did was through Oshpark @ $30 for 3 boards. I'd gladly spend the same amount for 10 boards with the same ship time - and have larger boards for development.

Max size is 100mm x 100mm is ~4" x 4" - which would be $120 through Oshpark

 

Ooooo! This is my first time seeing this - I may have to try them next time - last project board I did was through Oshpark @ $30 for 3 boards. I'd gladly spend the same amount for 10 boards with the same ship time - and have larger boards for development.

Max size is 100mm x 100mm is ~4" x 4" - which would be $120 through Oshpark

Eric Smith has used PCBway a number of times. Scot A. is now considering them for his next batch of 4-layer boards...

Eric points out that the price jump is huge if you exceed the 100mm limit. So, don't make the mistake of doing a 4" board. Shipping is about $25 or $30 so you want to order a bunch of boards if you want to amortize the shipping cost. I think Eric said that they did lump together all of the different boards ordered at the same time into one shipment at a single shipping cost.