I've done (well, my wife actually) done a few different etchings.
Used ferric chloride (mixed from granules) in the normal PCB dilution.
The first one I(she) used acrylic paint as the blocker, and it worked fine, but after rinsing it cool it off the paint began to bubble, not sure if it was the temperature change or what, but pain (acrylic) is NOT the way to go.
She also did some testing with 'liquid hard ground', which is a printmaking blocker, sort of like thin tar. This worked great, but is harder to remove after (you need a solvent).
For the last one we(she) did, she did patterns with masking tape, and cut further patterns with an exact. This gave surprisingly clean lines.
To get a decent etch I left it in for over an hour, agitating it regularly. The paint one came out after 10-15 mintues due to the paint reaction.
Here are the examples.
First, paint blocker, light etch (we liked the way it looked as is, so it was sealed after a light/random sanding):
Next, masking tape blocker, long etch, with paint afterwards:
The rats one is a rehouse, a boss ce-2 and a bigjam EQ in one. The 2nd one is a 4ms phaseur.