GrimLore
Bonsai Nut alumnus... we miss you
As the standard Jiffy tray is rather flimsy I do a quick modification or two to make them useful 
I start will plant flats that any Nursery is more then happy to give anyone free. I asked for 6 yesterday and they gave me 10 anyways -

I drill 1/8 inch holes for drainage in a Standard Jiffy Tray as so, nothing fancy -

Insert the Jiffy Tray into the Flat. Now you can actually lift and move it without it collapsing -

Cover for tiny cutting or seeds. You can also drill the sides for air flow if you feel a need -

I carried this tray over 20 feet without it folding or failing using this method -

If you need to not have them drain as if bringing indoors simply plop the flat and tray into another without holes -

Happy growing!
Grimmy

I start will plant flats that any Nursery is more then happy to give anyone free. I asked for 6 yesterday and they gave me 10 anyways -

I drill 1/8 inch holes for drainage in a Standard Jiffy Tray as so, nothing fancy -

Insert the Jiffy Tray into the Flat. Now you can actually lift and move it without it collapsing -

Cover for tiny cutting or seeds. You can also drill the sides for air flow if you feel a need -

I carried this tray over 20 feet without it folding or failing using this method -

If you need to not have them drain as if bringing indoors simply plop the flat and tray into another without holes -

Happy growing!
Grimmy