The official was a neat figure and all, but based on the art work the proportions were off. Superior Venom has odd proportions due to the art and that was what I liked about it.

Superior Venom head and hands.
Wonderman body and upper arms.
... smaller... parts used...
To be honest, I do not remember the recipe.
The legs are from that Lord of the Rings spider with the front two legs extended a bit.
The part that is connected to it to be able to insert into the back was sculpt with pieces from a model kit. Not an actual piece but the piece that you snap the parts off of.