Engineered wood? I suspect that means some variant of particle board, which I hate.
Do you have access to laminated pine panels (300mm wide) or glulam or 12-18mm plywood? That's what I'd use.
Looking at .co.uk web sites, a 1220mm×2440mm sheet of 18mm plywood costs about £25-£35. For three shelves, 1m by 1m in size, you'd need five strips, or about 1220mm×1600 of the sheet, plus five 300mm×350mm for the separators, so you'd still have at least 1220mm×440mm left, enough for a middle level backing.
In other words, a single full sheet is enough to make a similar shelf unit; you can even make it a bit wider (up to 1220mm, or 1.2m wide).
18mm thick plywood, even in Spruce (Baltic Birch is the Good Stuff), is amazingly strong stuff. Twenty years ago, I made a TV stand for a 28" old CRT TV that weighed a lot, so I used 18mm spruce plywood, and through mortises for the vertical pieces (i.e., rectangular holes in the horizontal pieces, with vertical sides and back through those), and the 100cm by 40cm by 40cm box was sturdy enough for a 100kg guy to jump on; probably strong enough to park a car on top.
Edging the edges to hide the plywood structure, if you want, you can do with thin strips of wood. Glue the strips on, then drill 5mm holes about 30mm deep, and glue in some dowels, say every 25cm or so. That will hold even if a heavy scope happens to rest on the edging, and won't cost much.
I didn't paint the plywood TV box at all, just oiled it. I like the look.
If you want, I can draw up a cutlist for a full plywood sheet to make a 122cm by 96cm, 30cm deep three-shelf bookcase. All I used with mine was a jigsaw, drill, a chisel (to clean up the mortises), wood glue, and wood oil (Ikea Skydd/Stockaryd/Behandla).
(Actually, if I were you, I'd first measure your devices and things you'd like to put on it. Maybe you want two high shelves, with upper one less deep than the lower one; or maybe split so that left side has two shelves, and the right side three. Maybe you know the shelves' heights already. I'd have a good think at it first, then do some drawings, maybe even a cardboard test, to see what works.)