A Small Gong Or Wok

Given the frequency at 528 Hz and the speed of sound, $\text{331.29 ms}^{-1}$,

$\lambda=\cfrac{v}{f}=\cfrac{331.29}{528}$

A fundamental frequency of half a wavelength across the gong, 

$d_g=\cfrac{1}{2}\lambda=\cfrac{1}{2}\cfrac{331.29}{528}=0.3137$

A gong of diameter 31.37 cm.  That's a small gong.  You can use a wok or pan of similar size, 32 cm; 528 Hz with white or brown noise from a speaker.