  Sheffield (2011) proposed an inventory accumulation model with two types of
products to study the critical Fortuin-Kasteleyn model on a random planar map,
and showed that a two-dimensional inventory accumulation trajectory in the
discrete model scales to a correlated planar Brownian motion. In this work, we
generalize the inventory model to $k$ types of products for any integer $k \ge
2$, and prove that the corresponding trajectory scales to a $k$-dimensional
Brownian motion with an appropriate covariance matrix.
