Ive been thinking of this for a bit lately.
Has anyone ever thought about making an in-greenhouse garden bed, or a large planter box for alot of you cacti to grow in? I think it would be pretty neat, as im not a fan of lots of pots.
If i was make a larger planter box, maybe, 1-2m long, 50cm-1m wide and maybe 20cm deep, how do you think they would go?
Obviously there's the problem that others dont like water as much as others, some are winter growers and etc.

Just seem's like an interesting idea, like haveing a portable raised garden bed.

Sounds like an interesting idea.

I guess I wouldn't do the same thing because I rent where I'm living.
I also find it easy to manage my plants if they are all in individual pots. As you said it's easier to control food, water, sun, etc.

What kind of plants were you thinking of growing in this bed Michael?

it can look cool. one grower here does that on the sides of his greenhouses. but only plants hardy plants in it because as you say, planting ariocarpus or something there would just spell disaster unless super carefully done.

I was only thinking just common stuff like common mamms, echinopsis balls, rebutia, what ever i can pick up around the markets and etc, maybe a couple of low growing cylindropuntia's.

Im not a fan of Ariocarpus, they just really dont interest me

I've seen planters with those sorts of species available at markets. Generally, I would think that provided the plants are fairly hardy you should have no problem with a group planting. The only thing I would be concerned about is the potential for one or two plants to outgrow the others and take over the planter. I'd hesitate to include anything ending in -opuntia for this reason.

I know that Echinopsis, Mamms and Rebutias all seem to tolerate each others' presence quite well, and are generally fairly hardy to boot. Some Gymnos and Feros can work well too.

One thing to be aware of is that a planter of the dimensions that you describe won't be overly portable. I don't know whether you want the planter as a fixed installation (in which case I reckon it's a good idea), however if you intend to transport it to another location you may find it to be rather unwieldy to move.