Not wanting plastic parts maybe a big issue and the dimensions you quote can be difficult. In the desktop market, for which most of these suggestions are about, we have the CubePro (https://www.idig3dprinting.co.uk/sho...ro-3d-printer/) and soon the UPBOX (https://www.idig3dprinting.co.uk/sho...rinters/upbox/) but my guess is that you need a production grade 3D printer and so you will need to be looking at Statsys range of 3D printer or that of 3D systems. Whether they will come in under $5000 may then be your big problem. Both of the desktop models I mentioned are under $5000, there dimensions are approx >25 in x & Y but the heights are limited to just 20-23cm. They will have some plastic parts but they do not use Open source software. In fact 3D systems produce a range of software packages.

I would not necessarily dismiss open source software, If the machine you get can utilise open source software then you will ulimately have greater control over your printing. bundled 3D printing software solutions can sometime be somewhat limiting as they are designed for the more, press-and-go style of printing. Open source software is not cloud based eg.. Slic3r and should pose no more of security risk than other proprietary software solutions, it will be dependent upon your own data use protocols.