Ele trabalha com gesso/Ele faz todos os tipos de trabalho com gesso

He works with plaster of Paris.  He makes all kinds of things with plaster of Paris.

Eu tenho muito carinho por ele

I feel a lot of affection for him.

He is dear to me.

Eu estou vendendo bijouteria pra complementar meu salarinho de fome

I am selling costume jewelry to augment my poor/meager/starvation wages/salary.

Last but not least, can I use all the following terms interchangebly?

trinkets, bijouterie, bijou, costume jewelry, junk jewelry and novelty

Trinkets are not necessarily "bijutereia".  They tend to be inexpensive and of inferior quality.  A keychain with the image of Pão de Açucar would be a trinket.

Bijouterie is French.  I have not heard it used in the USA.

Bijou is French.  I have not heard it used in the USA except as the name of a cinema.

Costume jewelry is an excellent translation for bijuteria.  Costume jewelry is sometimes quite attractive and may pass as "the real thing".

Junk jewelry is very cheap costume jewelry. 

Novelty items are often trinkets.  If a pipe has a picture of Maradona and is used to smoke cocaine, I would call it a novelty item.  A necklace obviously made for tourists to the Amazon would be a novelty necklace.