We happened to have an old PID temp controller and termocouple from an old
upgrade project and hooked it up to a 600W toaster oven. Most of our boards
are small so it fits into the oven just fine.

We put the boards into the oven and start the PID controller. Setting is
80C for 15 minutes, ramp up to 120C in 15 minutes, hold for 10 minutes,
ramp up to 160C in 5 minutes and immediately back down to 80C for 15
minutes. Open oven, do not remove board and allow to cool to room temp.

We got this setting from trial and error, u'll have to do the same and
settings for 4 or more layers will require longer times or ur plated
through holes might fracture.

Applying solder paste is another problem we went through. We made a jig to
dip the SMT leads in.

1 pc 3" square, flat glass base
4 pcs NT cutter blades (the snap off type, small)
1 pc NT cutter blade (Large)

Glue the 4 blades (sharp edge facing out) onto glass base forming a
rectangle (snap off some sections of blade to fit) does not have to be a
perfect rectangular perimeter.

Scoop some solder paste onto glass within the rectangle blade area, use
large NT cutter blade to spread the paste using the rectangular structure
as a height guide. You'll have a uniform thickness of solder paste to dip
ur SMT leads into. Don't press too hard, just enuf to get some paste onto
ALL the leads. Don't worry about bridging, solder mask and surface tension
takes care of *most* bridging problems.

Cheers
Terry