Rhys
Like you, I found something in the kitchen to store the 20 small blocks from the mini-blocker. I use aluminium foil food trays, from Asda, which are just big enough to take 20 blocks and put on the windowsill. 20 seems to be enough for me of any one seed type. I’m leaving a lot of seeds in the packet! The growing medium needs to be very wet to get good blocks. I think the water makes it slippery, so that it easily fills all the corners of the the blocker.
To set out the 2-inch blocks, which are much bigger, I use Stewart 100cm Growbag Trays, which are watertight for flood watering the blocks from the base. These trays have a flat bottom, so can also be used for mixing the medium and pressing down the blocker into when filling. They are available online from Crowders.