Rectangular

As part of a charitable enterprise for low cost hydroponics for small farmers in developing countries , I want to be able to connect 5 litre rectangular (not circular) lidded buckets together in an array so water can flow from one bucket into another. So imagine the farmer wants to create an array of 10 X 10 5 litres buckets, to be able to grow 100 plants , he would invest in 100 units of this system, connect them up and be able to fill one bucket with nutrient solution which would fill his whole array as they cascade into the next bucket. The farmer would the insert the plant net pots into the lids and his low cost hydro operation is active. The question is how to approach this. If one would DIY this one could connect the buckets by drilling holes and use tank connectors and pvc pipes at the required water level. This requires tools and labour which would make this method not very efficient and one might as well build a permanent tank with timber and pond liner If however we could mass produce rectangular buckets with lids that somehow slot into each other without leaks, now we have a very cheap scalable way of doing passive hydroponics with minimal entry level skills. I'm looking for ideas of how to achieve this. Maybe the buckets have molded pipe sticking out on one side a grommetted hole on other side and slot in each other like that ? Or maybe they have a simple lip one side that slots into the next bucket and cascades into it without of course leaking as that other bucket fills up. The key requirements: * rectangular to not waste space * 5 litres as this is enough for one lettuce plant * Slots into each other with no tools required * Leak free * Corner bucket to be able to create a 2 dimensional array of buckets. * Lids with holes to accommodate plant net pots (usually 2 inch). Not so important to focus on as it's an easy problem. Of course I'm open for ways to cheaply convert existing rectangular buckets with minimal tools and labour , but I can't see how myself.