Here is the schematic, PC board layout, and parts placement. Always breadboard first!
http://www.musicfromouterspace.com/analogsynth/vca.html
The function of this dual VCA is very similar to the other one. It uses one less chip but one more transistor. It uses the built in LM13700 buffers instead of OP-AMPs.
http://www.musicfromouterspace.com/analogsynth/newdualvca.html
This one uses a diode bridge.
http://www.4qdtec.com/cca.html