GoomGoom is a few component very low cost diy synthesizer. It is 16 voice polyphonic and multitimbral. You can find it at http://www.quinapalus.com/goom.html
The panel can directly control all parameters. Store each voice on its own. Put it in a bank of 16 channels. Store the complete bank on your harddisk. I have had contact with the inventor of the Goom and he made a special edition of the firmware for me so it can be controlled by the panel all the way, without the hardware panel.