The number to watch
Margin per profile against the metal rate. Aluminium moves with the metal market, and a selling rate set two months ago against a purchase price that has risen since is how a busy shop stops making money. Because purchase and sale both sit in one system, the comparison per item is a report rather than an exercise. Run it monthly and you will find two or three profiles where the gap has quietly closed, usually the fast-moving ones nobody thought to re-price.
Weight, length or piece — all three
The same section is quoted per kilo to one buyer and per running foot to another, and a fabricator ordering a full set wants a single bill for both. Holding the unit and the conversion on the item means you sell in whichever the customer asks for and the stock stays correct in the unit you buy in. Section weight per foot varies by profile, so it belongs on the item record rather than in somebody's head.
Section number, series and colour are the item
An aluminium shop carries hundreds of profiles across several series, each in natural, powder-coated and anodised finishes. Treating those as one item called "section" makes stock meaningless and rate errors routine. Each profile, series and finish should be its own item with its own code — which also makes reordering from your supplier a matter of reading a list rather than walking the racks.
Fabricator credit and long jobs
Your customer is usually a fabricator working a site job that will be paid in stages, so the material goes out over weeks and the money comes back later. That needs a credit limit set in advance, ageing so you can see which jobs are drifting, and deliveries recorded against the site rather than just the party. When a fabricator asks what he has taken for a particular job, you should be able to answer in ten seconds.