I don't have a clue what trays you are talking about, but since nobody has responded I will tell you one method I use. Cheap cat litter trays. They have a hole on each side in the middle. If you don't find them with holes, drill them. Use some kind of wire to make a hoop. Then cover the whole thing with a white plastic bag by actually placing it in the bag, which diffuses light better than any transparent humidity dome. Works really good for cloning. Never understood why humidity domes are transparent. Everyone with experience or that has read even one gardening book knows that clones/cuttings and most seedlings do best in subdued light.

The wiring I use is fencing wire. Bendable but keeps it's shape. It's also not going to rust like a coat hanger will. I also use these for home made row cover hoops in my soil garden in spring. Just buy a roll and cut to length. One $12 roll made hoops for my trays and all my garden beds and I've only used half of it.

Hi,

I know this is a very late answer, but your query came up as I was trying to find domes for my Perma-Nest trays.

The Mondi ones don't fit at all. They're not long enough, and slide off.

I just ordered some that are supposed to be made by Perma-Nest from the Indoor Gardening Supplies website. I don't have them in hand yet, so can't report on the fit (but will try to once they arrive).

I've used a Mondi high dome (with an adjustable vent, which is very clever) on top of a "cheapie" growing tray, and set that inside of a Perma-Nest tray, to make it easier to lift in and out of my DIY light stand. Another thing I've noticed with the Mondi domes is that they yellow after about 10-12 months under my 3-lamp florescent fixture (2 cool white + 1 warm white). I got the P-N ones which are supposed to be much thicker and more durable because of the poor fit and I figured that for a few bucks more, if it really was that much more durable, that it would be worth it.

Hope this helps,
Jane

ps - Joe, I REALLY like that DIY idea with the plastic bag! What I've read is that diffused light is much more beneficial. I'm going to try something like this myself, just using leftover chicken wire to make the tent within a heavy duty P-N tray. Great idea!

Here is a link that might be useful: Humidity Domes for perma-nest trays