Ok Stefan,

Here I am.

In this video http://take.ms/obpkW you can examine the method I used to create the solid engraved heart.

I'm pretty sure there are at least other 2-3 different methods, but anyway...this one worked for me.

The video file is rather big (258 Mb, 3 min, hd, 15 frame/sec) and I hope you have a fair connection,
but if you want to play it smoothly I suggest you to download it first.

Here are just some notes regarding some portions of the video :

1) Around 00:50 sec I perform an heavy rebuild that on my laptop (i7 4790K 4.4 Ghz) took bout 32 sec,
therefore in that point I paused and then resumed the video.

2) From about 01:42 I start to use the "shell" command in order to get the solids that I will later use to engrave the heart.

3) At 02:10 you will see a failed attempt to perform a "shell" command on the biggest surface.

HERE'S THE TRICK!
I PERFORM A TRIMMING OF THE BIG SURFACE IN ORDER TO OBTAIN SMALLER PIECES THAT WILL NOT FAIL WITH THE SHELL COMMAND.

I hope I made myself clear.

Best,