On Sun, 20 Jan 2019 04:29:12 -0800 (PST)
jkn wrote:

The drawers are quite large, so I would need lengths of something
like 700mm.

Any thoughts as to other sources of cheapskate materials I might
consider for this?

Thin sheet steel as used in domestic white goods (so free if you get
there before the scrap man - or try Freegle). Fold it double to stiffen
it (or fold in a L or T shape for extra rigidity) Cross-dividers can be
tack-welded in place.