Parks Bio Dome seed starter

After learning of the Parks sponges and the Biodome last night I had an idea to satisfy a need to start seeds for the hydroponic unit without using the unit in germination mode, as there are already established plants.   I also need to start about a dozen plants for the outdoor garden every year which I have relied on large peat pods for. 
The interesting trait of the Biodome is the fact that the part that holds the sponges floats on the water keeping the bottom of the sponge in the water no matter  how much water is added. 

I came up with a quick POC to see if a 3dprinted holder floating on a piece of foam would works more or less the same as the biodom.  If so, I can make a lager version with 15 pods that would fit in a rectangular plastic shoe box. 

Just have to wait for the sponges to arrive and make sure they fit tight enough once wet.  Only had an unboxing youtube video and the measurement  in the FAQ for the product to go in to design the holder.

This is just a 1qt soup contain for proof of concept.

The sponges have arrived and time to test this out.  I was unable to get the Romain Lettuce to germinate in my DIY Bounty so I am going to try the seeds here.  I also bought some Iceberg lettuce seed from Park since I was paying shipping for the sponges.  The wife prefers Iceberg but not sure it will be good to grow in a multi pod garden.  May try just using a single container and the Krathy method for a single head of lettuce.  Also if it would ever rain, can try planting some outside since Park claims this variety is  heat resistant.. just not sure how critter resistant it will be!

Anyway, I digress.. I put 2 seeds in the sponge hole and 1 in a crack in the top of the sponge. 2 are Romain 1 is Iceberg.  Time will tell..

Picture taken before I put the seeds in.  Let sit for a few minutes to make sure the water would wick up the sponge and it of course does.