this is a remix/ combination of the cartoon heart (https://www.thingiverse.com/thing:3235897), and the puddle from (https://cults3d.com/en/3d-model/art/melted-lego-derretido) along with some filleting and other customisation. I did this as my lesson in Tinkercad at the local community learning class.

the instructor printed it in a Bambu printer with no supoprts - and in the upright position. I believe it's 5% infill, but no idea on pattern or material (presume PLA or PETG)

My heart melts for BKA

All in Tinkercad -
1) I trimmed away the lego block from the melted block to get the puddle.
2) I brought the heart into the same workspace in Tinkercad
3) I tilted the heart to one side by ~10degrees
4) I expanded the puddle in size so it was as big as the heart for stability
5) I lowered the heart into the puddle to form a decent sized connection
6) I made a "fillet: to strengthen the connection by making a short section of elliptical pipe, then a matching elliptical torus as a hole to create the fillet (radius 2mm)
7) - brought it all together and then trimmed away the bottom 0.3mm to clean the bottom.