Homebrew PCBs

You can use plumbing solder paste (with flux) and paint the board with
it., then you heat the board with hot air or a hotplate..
The paste can be thinned with water to make it easier to apply, and it
is much cheaper than SMD paste.
Excess paste in bare areas and flux just washes off with hot water.

There will be lumps if you apply too much or unevenly, in that case
carefully wipe it off with a paper towel wad while molten.

ST