Is contorted hazel the same as corkscrew hazel? If so, then yes it is safe. I'm not sure of the dimensions of what you have there, but they need to be around a centimeter in thickness. More or less is okay but not for everyday perching - their feet need to go about two-thirds of the way around the perch. Variety is more important than anything else. And roughness is fine, as well.
To get them budgie-ready, they need to dry out, knock off all the growth nodes and give a scrub with some mild dishwashing detergent, rinse in a mild vinegar solution, and dry in the sun. If you have no sun, then the oven will suffice, but don't overcook them.
Are they for a cage or aviary? If an aviary, then the thin bits will give the birds some lovely foot exercise, as long as they have some thicker perches to rest their feet at other times.
We are not Vets, Avian or otherwise. If you have any serious doubts about your budgies' health an appointment with an Avian vet should always be your first point of call.
I was planning of only using the thicker ends for the perch (I have several natural thick ones that I brought from the shop but wanted to add something more fun) The finer bits left over i was planning on bundling together to make a toy.
Yes im sure they said it was the corkscrew kind and theres a straight version too.
Its for a large cage.
I have got some white distilled vinegar but it says malted on it - not sure if this would still be ok? Im planning on getting some f10 soon.