Horticultural catalogs carry the clear, green, and brown plastic netting and the Sphagnum moss to contain the root ball for making these if interested.

Or it is even cheaper to buy the moss and a small roll of the plastic fencing and make your own. Lowe's and Home Depot carry both this time of year and color of the netting is the only limitation.

Plant selection needs to be limited to those with the same light and water needs otherwise you have to water 'something' almost daily. And they will still need at least weekly attention for trimming, deadheading, etc. to maintain appearance. I recommend using purchased 'houseplants'. The small 6" pots of them are inexpensive and easy to ball up.

As an alternative consider one of the so-called "living wall planters". Linked an example of one type below but there are many. Scope out all the various pics attached to it for ideas. They can be attached to walls or hung suspended.

Dave

Here is a link that might be useful: Living wall planters

They are very cool looking, especially that last picture, but they must take constant maintenance and clean up. Are you also tasked with daily care taking?

If a perfect sphere is a requirement. You could start with a hollow rubber ball - cut off the top - pierce holes for drainage and air, and then hide it in sphagnum moss and netting. It would also contain the dirt and water better, keeping it from dropping all over the office floor. It would actually be a "pot", but not recognizable as one.

sempervivums are often grown in a globe shape (usually 2 wire baskets wired together). The houseleeks will grow together and can be kept in the same shape for several years, removing offsets and filling in dead centres.

This style is called kokedama. Good luck.