Hi Mark,
A cheap suggestion would be your geometries, if you add some spars along the top and bottom you could likely do away with the glass (it looks like this is the densest material).
If you can bind the two coils together and remove them from the glass, and replace that with some PC that will yield large weight savings.
(to put my thoughts into a photo, something like this : https://www.bunnings.com.au/all-set-100l-grey-and-green-heavy-duty-storage-container-with-flat-lid_p0406871)
