You could use a Grasshopper definition that creates the parametrical planter box as well as defines it as a block within Rhino. The Elefront add-on can create and update Rhino blocks from Grasshopper.
Then you could either use the definition with “externalised”, published sliders that you could control from the remote Grasshopper Panel inside Rhino.
Another possibility would be to use Grasshopper Player which can run external Grasshopper files kinda headlessly. For more on that check out this thread full of great examples.
To get it into the Rhino properties palette, you’d probably need to script it as a plugin.