'Other' Constructional and Allied Systems Info & Downloads
AtoZ (Metal Mechanic) Construction Sets
AtoZ (Metal Mechanic) construction sets have parts similar to both Eitech Construction and Meccano and are classified as Polylong(1) type sets. AtoZ is the brand name of Padgett Bros who are a Major Importer & Wholesale Distributor of Toys, Nursery Goods, Pre School Toys, Branded Items, Arts & Crafts, Tools, Housewares, Garden, Pet Products & Grotto Toys. They have a website https://www.padgettatoz.co.uk/BOYS/METAL-MECHANICS-463 from which the pictures of additional sets shown below were taken in summer 2020. Whilst the boxes all have the AtoZ logo on them, the instruction leaflets are obviously generic as the do not have any brand name on them. They are almost certainly manufactured in China. Judging by the various styles of sets they may well come from more than one manufacturer.
Info from the Metal Constructional Systems Database for POLYLONG 
2003 to in production in 2018 and continuing
25 (see comment *1)
4.2 (see comment *2)
Bolts: pan (crosshead)
Steel with a Bright Zinc plated finish
6.5(see comment *3)
Various Sets (see separate list) from Polylong & other makers. Most parts as CONSTRUCTION  but some others. *1 Mod.1 & finer for Motor/Gear Unit.. *2 Square holes in some RCEE sets, see TRONICO [a]. *3 6.1 & 7.4 also reported.
Below there are manuals/leaflets which can be downloaded by clicking on the appropriate image.
An instruction leaflet for an AtoZ Metal Mechanic set. From the manual front cover it looks as though this set is also sold under the Metal DIY Model name.
Photos of an AtoZ Metal Mechanic set. Note that the coloured parts in this set were plastic.
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