Option 1: DIY. fun, but extremely time consuming
Making a large thermoformed acrylic dome for the front of the sub yourself at custom dimensions is possible, but it's a lot of work, it is a project of its own. If you want to go down that route you will need to invest a lot of time building custome tooling and buy a bunch of machines to produce heat, create a vaccuum. I don't think you have the time to do that.
Thermoforming a large dome with advances machinery: https://youtu.be/5ufH44Y7kQA?si=BB7-k83d3uigLww4
If you don't have a large setup you can hack/DIY it: https://youtu.be/RNAc0C8nApc?si=TUTL9j-J_ap-SKa0
Bending small pieces of acrylic with gas burner: https://youtu.be/s5nP7MDf63Y?si=sx2bTebCkcr4JFaB
If you have access to a very large oven, that's how you can prepare large bending: https://youtu.be/45ivldW3eIQ?si=FUN7Tu5rHD7-HhUBhttps://youtu.be/QhQhy7v1F5M?si=CBCWkVEnN6Y2WERq
You can also use a heatgun, on a THIN acrylic sheet: https://youtu.be/ITalTq06qsc?si=Y_Z4bnrHIbZHeAos
There are many ways to do this, but don't expect to get right the first time if it's your first time.
Personally, I think you DON'T have the time to make a form, waste a bunch of plastic sheets to gain marginal performance.
Option 2: Sub contract. Possible, but can be expensive with longer lead time
If you have money, and a design, they are companies in Singapore that can do it for you:
- Singapore thermoforming: https://www.shinetechnology.sg/thermoforming
- Singapore thermoforming: https://kingsmaterials.com.sg/acrylic-sheets/
- Singapore thermoforming: https://www.highie.com/services/fabrication-services/
- Singapore Acrylic services: https://www.acrylic.com.sg/
- Singapore Acrylic supplier: https://aikhock.com/product/acrylic/
- Shenzhen: https://www.topthermoforming.com/about-us/ The lead time might be too long also, but you can give it a shot.
Option 3: buy existing dome. Cheapest, fastest, with guaranteed results
I would rather advise you to buy an existing acrylic dome, they are affordable, come in many shapes and sizes, with consistent thickness, and good optical and hydrodynamic properties.
Another good place to buy a dome is window dealers. Roof domes are sturdy and reasonably priced. https://www.terreal.com.sg/product/dome-with-glazing/
If you don't need a dome, but just need a curved "Windshield" I would simply cold bend a thin sheet of polycarbonate that you can buy as roofing material: https://www.amazon.com/exproyzk-Polycarbonate-Cold-Flexible-Resistant-Greenhouse/dp/B0BJ6YGYPZhttps://www.youtube.com/watch?v=14dZwwagiFs
Even in Artfriend, they have many sizes, some quite big and in stock in Singapore. Your "problem" could be solved in under an hour by just buying an acrylic dome off the shelf. That's what I would do personally.
Conclusion
The perfomance gain from a DIY dome in my opinion might not be that great for the time and money investment, which would be a lot. I would buy an existing acrylic dome, or bend a simple flexible sheet of roofing polycarbonate and focus on the other work you need to do - which is a lot.
And, and giant domes? Yes!
