My way of constructing it was to solder a 14 pin IC holder on the perfboard and first start connecting the pins of the various nand gates: so i put a blob of solder between pin 1 and 2 and between 8 and 9. Then I took a bit of wire and connected 5 with one and 2. Then I took the components and found them a place as close as possible to the connections that needed to be made and used wires at the underside of the perfboard to connect everything. That seems daunting, but in fact it proved quite easy, just make sure that you cross out the connections you made with a felt pen on a print of the circuit and you'll be fine.
You could add the switch to switch off the supply voltage, but I did not bother, i just unhook the battery. You could also use a switch as indicated to switch between preflash ignore and no preflash ignore but I did not bother with that either.
It is possible to omit the 9Volt battery and to feed the circuit from the sync jack (via a resistor a diode and a zener) but I would not bother. I tried it and it works for some flashes but not for others: apparently the load on the sync jack can influence the recycling time.
PCB: it is of course very well possible to build this on a PCB and you might be able to make it pretty small if you use smd components.
I have added a fritzing file to print the PCB. Realize though that I have not build it on this print, I uesed the perfboard as seen above. I have added the PCB design
for your convenience and I double checked it, but I have not tested it (yet)
I put my finished circuit in a small translucent plastic box, the kind that is used to pack bolts, nuts and screws (I use a lot of these boxes in my projects). They are quite handy, they are basically free as I already bought the bolts and it is a kind of recycling by keeping them out of the waste circuit. The box is translucent enough to still let the phototransistor/-diode pick up the flash