cyplesma
These 2 extenders are all I have so far. For these 2 I am using the Breadboard Prototype PCBs available at Radio Shack (276-0150). The one with the switches on it also has several female pins soldered to the board so that the switches can be configured with a pull up or pull down resistor. These resistors can be changed as needed. The switches I got from Electronic Goldmine a few years back, they were 5.00 for a bag of a 100. I have them mounted on their backs as opposed to their feet which faces the bus lines.
The extender with the LEDs on it has one set of LEDs (8 red ones) that are hooked with the same female pins put are used individually with a resistor mounted on the board via the female pins. I use the female pins to put the resistor in so it can be changed if need be. The other set of LEDs are the clear ones, but light up green. There are 11 of those on their side of the board and they use the 2 center bus lines to connect to. Again I have the female pins soldered to the board so that the leds can be used from the gnd bus or the VCC bus with a dropping resistor and another point to actually control the LED.
The female pins are from amazon: http://www.amazon.com/40Pin-Single-2-54mm-Female-Header/dp/B00ZBS4T12/ref=sr_1_2?ie=UTF8&qid=1453610774&sr=8-2&keywords=female+solder+pins+headers
Well it seems Amazon has gone crazy about the way they are pricing these female headers. I got 10 for 7.91 back in 2014. The prices on amazon seem to be out of control as of now (1/24/2016).
just added one of 2 boards I use for potentiometers. This as noted on it is for 3 10K linear potentiometers. The second one is for 3 100K linear potentiometers which is currently in use on a breadboarded battery desulfator circuit currently doing its job on a battery.