This is a interesting idea.
You need
ribbon, riband or a rope (maybe untreated hemp from a hardware store)
There are two options.
From a buttplug or from the waist.
From the waist:
make a "belt" with the rope and from behind pass it bewteen your legs to the belly button, measure, cut and make a knot at the tip. Then measure from one of your nipples, all the way to the knot and then to your other nipple. By the middle of the rope tie it to the tip of the first rope.
By buttplug:
The same but instead of a "belt" attach it to the buttplug
Then to the second rope, attach clothepins (or use Ruber) to keep it attached to your nipples (maybe You need more than one)
is your new underwear for a walk.
Now
You can use your vib (low setting) or some sharpies (5, or as many as You feel comfortable)
Get it inserted in your vagina
Feel free to adjust by your nipples (because i think is easier, not necesarily) the tightness of the rope untill You are comfortable that it Will not fall.
Use a su sundress or anything that doesnt help the rope
And then go for a walk wherever You choose.
If anything falls from your vagina, be Nice and pick it up and get it back inside you.
And be happy, You could try to jump to show your happiness