All recommendations are welcome. In particular how to vibrate a two part mold without it breaking apart. I did not weigh the mix and water, but i suspect i used too much water. Also added about 2% plasticizer.
2 minutes would not be near enough to jog out all of the air bubbles. Ideally, vibrating the slurry and not the mold would be best. You can rent something from a concrete tool rental company. Dunno how far you are from something. Also, in the same vein that anything is a dildo if you are brave enough, any rotary motor that spins off balance is a vibrator if its off enough.