Argo needs doghouse

Hello I'm Matthias. I'm 21 year-old student. I'm asking you guys for a help. My neighbor is 73 years old lady-Anna. Her grandson with his family moved to another city which is about 400km away from her and he must left his dog...IDK why...(hungarian vizsla named Argo) with his grandma. I was quite angry with this decision although it is not my bussiness but I love animals especially dogs and I was sad to see bored Argo just stuck in her yard. So one day I asked Anna if its possible to take Argo on walk. She gladly agreed and since then I'm taking Argo on walks almost every day. I'm also sometimes buying him treats and some proper dog food because Anna is feedim him only with leftovers. But here is a problem. Winter is coming and Argo is sleeping in an old barrel. No isolation whatsoever. I would like to buy/build a doghouse for him. I would prefer to build doghouse because its cheaper than buying doghouse from petshop. I think 100 € would be enough. Any donations will be truly appreciated. Thanks a lot! I will post photos of Argo and doghouse if I will receive money to keep you updated. Sorry for my English.