The part where the real magic happen, also called the tub, is a large sized dishpan that I purchased at the local big box store for less than $5.
You may be surprised at how easily it is to come across old end tables. With any luck, a family member or friend will have one they would pay you to take off their hands. If you do find yourself in the position to purchase one, check at yard sales or thrift stores.
You don't need anything special. The most important aspect is that the tub you select can fit between the legs. I have flipped the table over so you can see what I mean. I suggest taking a tub with you while you table hunt.
Once you have found your table, simply trace the bottom of the tub onto the top of the table and cut it out. It's important that you trace the correct side because it's the lip of the tub that will keep it from falling through the hole. My father cut mine for me in less than 2 minutes.
Depending on the height of your table, you may want to trim the legs down as well. We cut off a few inches to make it more height friendly for toddlers.
Then you simply drop in your tub and fill with goodies! Here I have added green rice and animals from the grasslands to go along with our study of biomes. I also like to lay out items to scoop and pour with.
I tend to stash the extra items on the shelf below. The kids enjoy finding what I've hidden down there. I placed my table on an old floor protector which helps with some of the mess.
As you can see, creating a standing sensory tub is relatively easy and extremely budget friendly.
And if you'd like to a quick tutorial on dying your own rice, check out this post from Mama Jenn.