Not with these handy parts any more!
These are complete programmable micro controllers that could be stuck to any solderless breadboard. Easy to program and easy to interface.
The big advantage is, that you don't need double side PCB, you don't need a custom PCB at all, you can also built it with common bread board and some wires too.
Step 1: The schematics
You need the power sources.
Then you have to tie the reset pin high, with a pushbutton to reset the uC.
And finally you need the three other lines to program the uC, Mosi, Miso and SCK.
I will explain this for the Attiny2313, but other uCs are as easy as this.
In the pictures to this step, you find the most simple schematic, then one with the ISP socket and the last one with all the pins routed to pin headers.
Step 2: The board
You can built this on some blank perforated board or you can etch a dedicated board for it. I chose the second way, because it is very clean. On a blank board you would have to use wires to connect the pins according to the schematics. But that's also ok.
In the two pictures you can see how I routed the schematics on my board.
If you want to make your own board, you can use the pdf with the 1:1 printable version.
Step 3: Solder the parts to the board
After you etched your own board, drill it and the solder on the individual parts to it.
The pins for the bread-board adapter are pushed through and the soldered from the bottom side. Although this is not ideal it should normally work.