Tillandsia (Air Plants) are very low-maintenance plants. To know more about them and its proper care, you could easily check with Mr. Google.

I'm currently in Japan and saw these from a Daiso (major thrift shop) nearby. Imagination kicked in and thought they'd look good on unique planters.

Note: this Instructable is not only limited to keeping Tillandisia.

Step 1: Forage

Materials

your plants
empty PET bottles with caps (cleaned, dried, plastic labels removed)
large scissors or hacksaw
utility knife
super glue
sandpaper
paint, craft paints (your choice)
paintbrush
your imagination (a must)

Optional

silicone sealant
varnish (water-based, or whatever is available)
paper clay or wood putty

Step 2: Guillotine

WARNING: You will be working with sharp tools. Being careful is a no-brainer.

Cut the whole neck, up to the neck support ring using a utility knife+large scissors, or by using a hack saw.

Sand down the burrs from what's left of the neck to make them smooth and leveled.

Using a utility knife, cut off the cap collar (the ring that's left when you twist-open the cap for the first time).

Save the caps for later. They can be used for accessories.

Don't throw away the rest of the bottle just yet.

Step 3: Dr. Frankenstein

With all the mutilated PET bottle parts around, this would be a do-as-you-like step.

What came out of my head are the planters shown here. You may use them as reference for your own, or do feel free to copy it if you like.

Using your utility knife and scissors, cut away what you think would look good on your sculpture.

Attach parts using super glue (because you're excited and want it to dry immediately). Once dry, there may be gaps where the two materials meet. Use the silicone sealant (or wood putty, or paper modeling clay if you have some lying around) to seal these gaps and spaces. Smooth them out using your finger (then wash them off from your finger immediately).

Step 4: The Picasso in You

Again, it all depends on your imagination when choosing paints and how to paint them. If you like to leave them bare, that's good too... it would have a glass-like effect. However, traces of sealants and putty would be an eyesore.

On the horizontal design, I first painted a primer so that the final paint would stick better. I chose black (like my soul), but you can use any color you like. Then I got this "Diatomaceous earth" paint from Daiso, and painted it on my sculptures. To have a textured effect, I painted the second layer with a dabbing method (or lightly stabbing your sculpture with the brush's bristles).

The pot-like sculptures, I chose to have it smooth. The goblet-shaped planter, I left it unpainted.

Optional (for you) : I wanted some kind of sheen on the horizontal one, so I varnished it with a maple-colored water-based varnish. The others with a clear matte varnish.