Is creating a Flesh Golem considered somewhat evil, like Necromancy?

I would say yes due to using corpses.

then I'm in, sign me up.

Quote from glimmb0 >>

Is creating a Flesh Golem considered somewhat evil, like Necromancy?

 No, it is not. Necromancy (or, at least, the spells that generate Undead creatures) functions by exploiting the soul of the victim and using its energy to power the undead. Golems (including Flesh Golems), on the other hand, are powered by Elementals which are summoned inside of the body once it has been built. The bodies are simply used as the material to construct the body. However, some degree of graverobbery is usually involved in obtaining the materials to construct a Flesh Golem, which is illegal in most places. 

Just don't abandon your new science son to the elements because you got his eye color wrong. 

Besides the Manual what else do you need to make a flesh golem?

60 days and 50,000 GP for purchasing materials, and one could assume the ability to purchase said materials.

That is perverse and evil to desecrate the dead to harvest parts to create an animated flesh construct. I think there is a measure of evil to perverse nature like this. It is like saying Dr. Frankenstein was not a bad person for stealing body parts of other people and using them to create a monster to bring them all to life.

Would your stance change if the body parts came from willing individuals, who consented to the process before death? What if the Golems were being constructed to safeguard towns? What if peasantry saw it as an honor to offer up their remains to protect the burial site of a widely beloved ruler? Maybe this is the sort of thing that can elevate common folk to knighthood, imparting those benefits on to their remaining family; Which would serve to remove a bit of the cultural taboo. I could see a number of good aligned gods condoning this sort of thing, in the right circumstances; Far more than the same circumstances with Undead.

I agree with the notion that there could be exceptional situations where it might be acceptable, like consent. But, this would be extremely rare, as the common folk would always view this as supernatural and on par with being undead...which would always be seen as evil. Having a automaton version of a deceased loved one, even to guard a city, I can;t see as normally being widely accepted and normal...and if it were, those outside the city surely might not.

Finally, now I can be Victor Frankenstein!

In my old (albeit AD&D not 5e) game I had one of these and for the most part the trick was to collect and find ways to preserve pieces not of humanoid races, but bigger bestial ones. Stuff like the arms and legs of an ogre, heart of a hill giant and so on. There's no point in graverobbing humanoid settlements cause you'll end up with a really scrawny golem, and the pieces would likely have decomposed beyond usefulness by the time you get them. In Descent into Avernus there's also a fiendish flesh golem using devil & demon parts, and I've seen a Draconic one in a 3rd party bestiary.

That makes it at least a little less morally reprehensible but not greatly. Still, in 5e it doesn't seem to indicate this kind of behaviour is required & honestly you could just flavour it as growing the flesh samples yourself like some sort of giant cloning vat. I don't like that though, seems mega expensive for a normal campaign. I'd rather be able to lower the cost if I actively hunted down the components, which in this case would largely be the body parts (but not exclusively). I've even considered using this to re-animate a dead party member before...

Quote from Blue0440 >>

Quote from glimmb0 >>

Is creating a Flesh Golem considered somewhat evil, like Necromancy?

 No, it is not. Necromancy (or, at least, the spells that generate Undead creatures) functions by exploiting the soul of the victim and using its energy to power the undead. Golems (including Flesh Golems), on the other hand, are powered by Elementals which are summoned inside of the body once it has been built. The bodies are simply used as the material to construct the body. However, some degree of graverobbery is usually involved in obtaining the materials to construct a Flesh Golem, which is illegal in most places. 

 Who said they had to be from graves? 

Player characters will probably have dead bodies from combat encounters so you could just use those bodies. Collect them in a bag of holding, portable hole or the like and voila, you have an abomination made from humanoid corpses that obeys your commands until, well it gets below 40 hit points and kills you and your friends. 

My favourite magic item for precisely that reason.

well i mean in real life you can buy cadavers from medical stores I'd assume you could the same in dnd 

50,000 Gold, 60 days or 6 workweeks, and two 5th level spellslots for a singluar CR 5 creature