Antique Grain Focussing Magnifier

No doubt this item is in common use in darkrooms across the country but I have never found found one myself.  Pre-War may be a better term than Antique but the magnifier is uncoated and the general build rather  heavier than one has come to expect.  I normally use a French Scoponet which I have shown for comparison.  As received the older item had a damaged mirror.  This raised the question of how to make a new mirror, preferably a surface mirror although I suspect that some on the market are not of that type.  I found a IKEA mirror for pocket use with the surface deposited on plastic sheet thin enough to cut with a craft knife.  I am unable to say how the mirror is coated but above all it works without a double image and gives accurate results.  I feel the oversize mirror helps in use and brightness is no problem. In case you wonder the cross hairs are located in the tube below the eyepiece.