as far as I'm aware, A3D have been trying to get their printing...

as far as I'm aware, A3D have been trying to get their printing systems to work properly since 2016, i.e. no accreditations, qualification of parts and no parts in service yet, and printer orders have been zilch for years. Although they were selling printers from 2016, they haven't worked well due to the cheap laser that's used to melt the powder, so parts have been difficult to certify/qualify...
I think they've had some very recent success, but are struggling with any meaningful revenues... they got a defence contract for $49k recently which started bumping their SP up, which in my opinion is hardly material funds to keep the business going!!
Revenues are very poor, so unless they get $M contracts like AL3 and TTT then I wouldn't consider them comparable at all. AL3 for instance has both accreditation/certification, better customers, and $M contracts for printers and parts

My view for A3D's SP rise is hype (again) plus both AL3 (AML3D) & A3D have similar names/ticker codes, so I reckon some investors have mistakenly brought A3D when they were meant to buy AL3 (AML3D) when AL3 have had all the recent news!!! (compared to A3D measely $49k contract)

I hold AL3, but had to sell A3D and TTT at losses a while ago as I grew doubtful of their respective tech processes acceptability within the industry and therefore ability to ever make profit! I reckon AL3 will be profitable this FY due to their US facility and contracts coming...