Use the mold_all_compents 3mf file to print everything for a single mold. Printing without a brim works fine, 50% infill works for me.

The pillars might cause some stringing, but this can be removed quite easily. To assemble push the pillars into the plus shaped holes on the edge from the underside of the mold box. Push them in place by pressing the mold onto a sturdy flat surface like a table top. The pillars have a slight taper which makes them snap into the holes more easily. Earlier versions had the taper at the bottom so they could be push in from the top but this was both harder to print (without them falling over) and breaking the pillars when to much force was applied.

For the top mold fit the little air inlet stick into the hole in the cylinder (with the cross on the bottom) and put both in the hole in the center of the mold. Carefully pushing down on the air inlet to make it lie as flat on the bottom of the box as possible. When inserting the inlet it works best to keep the side that was flat on the printbed pointing down.

For casting the bottom mold just add the flat cross in the middle removing the cylinder if necessary

Curing time 7 hours. However when cured at a 60C temperature it takes 20 minutes.

Soft flexible silicone and very long and pointy hypodermic needles aren't the best match. Therefore use a Dremel (or rotary tool) with a cutting disk to shorten them. Before you start lay them on top of the top bubble to see what length you should keep, they should reach across the wall but don't need to be in the center. After the cut use the disk to sand the edges of the tip slightly so there is less risk of it puncturing things.