The question asks for recommendations of sewing machines that have a certain type of appearance. I can't answer that directly, but maybe I can expand your options.
If you were sewing your own sails, tents, or outdoor canopies, or upholstering furniture, the appearance of the sewing machine probably wouldn't be that important to you. It would just be the available tool. Consider whether the significance of the sewing machine's appearance is related to the fact that you want to use it to make clothes.
There's some cultural stereotyping that sewing clothes is a "feminine" thing, but most tailors of men's clothes are men and they don't view their work as "feminine". I suspect that among tailors, you would find roughly the same distribution of characteristics we associate with "manliness" as for the population as a whole. It generally doesn't require the physical strength of, say, construction work, but neither does a job like computer repair, and we don't think of that as "feminine".
You've defined "manly" characteristics for a sewing machine in good, objective terms. But many of these seem like conflations; some are design characteristics that are merely practical.
- Rounding is a safety and ergonomic characteristic. It is more comfortable to handle a smooth surface than an angular one.
- Metal rather than plastic relates to cost and age. In "olden times", the plastics available today didn't exist; everything was made out of metal. If there were plastic parts, they were something like Bakelite. For sewing machines manufactured now, metal is used on high-end, professional equipment that is designed to last a very long time under heavy, continuous use. Machines made for the consumer market are generally plastic, which is partly how they control cost. If you want metal, it will put you in a different class of machine and you will pay more for it.
- Drawings and information are a user-interface thing, generally targeted at amateur vs. professional users.
- Color is a matter of personal preference. Manufacturers try to appeal to a broad range of customers by giving people a color choice (just like car and appliance manufacturers). There's also a little usability benefit for some colors (e.g., better contrast with thread, the amount of reflected light that can be easier on your eyes depending on lighting). If a manufacturer offered a machine in a color like pink, I might suspect that was targeted at a feminine audience. But basic white or black is genderless.
- Not sure why shininess would be associated with feminine or masculine. A shiny surface is typically easier to clean and maintain, but can also create glare from reflected light. A slightly matte surface is the best compromise. This kind of finish might be easier to find on a higher-end machine than a low-cost consumer-grade machine.
Rather than trying to define or attribute appearance characteristics as masculine vs. feminine, you might find it more useful to contrast "consumer" vs. "professional". You'll pay a lot more for professional-grade, but it will also hold up much longer and be more serviceable if you use it a lot. Professional-grade machines will generally look more heavy-duty and utilitarian. They will also be designed to do their core tasks well and are less likely to include endless "features" you will never use (which also goes to the markings on the machine.
A sewing machine is basically just a tool. There may be some machines targeted at a feminine or masculine audience, but that would be marketing gimmicks, designed to appeal to people for whom appearance is more important than function. Professional-grade machines are not designed to appeal to gender, they're designed to do the job well for any user. How their appearance is perceived (manly vs. feminine) is all in the eye of the beholder. Consider a high-performance automobile. Whether it has smooth curves or sharp lines, and regardless of color, it is attractive regardless of gender. To the extent it looks feminine or masculine, that is something artificial that individuals project onto it.
If you're going to invest in a machine, spend your money on performance and quality. No professional-grade, heavy-duty machine is really going to look non-manly.
