There are no identification marks on the original device,however i have seen a couple of mine with spurious markings added,crudely stamped broad arrows with r.f.c. and dates.Which are completely wrong for any W.W.1 air dropped munition.I cannot remember exactly when these were made but its certainly over severn years ago.
It was a real pain to get the correct type of TIN plated steel sheet of the correct gauge,modern tin plate [if you can find it]is float plated and does not have the characteristic chrystal formation on the surface,as found on dipped tinned sheet.
I found a tin box manufacturers in London who had old stocks of dipped tin sheet in several thicknesses,bought the lot.