Formal:
* 当然,我很乐意与您一起制作[something]. (Dāngrán, wǒ hěn lèyì yǔ nín yīqǐ zhìzuò [something].) - This literally translates to "Of course, I am very happy to make [something] with you."
* 好的,我很愿意和您一起做[something]. (Hǎo de, wǒ hěn yuànyì hé nín yīqǐ zuò [something].) - This translates to "Okay, I am very willing to do [something] with you."
Informal:
* 好呀,我很想和你一起做[something]. (Hǎo ya, wǒ hěn xiǎng hé nǐ yīqǐ zuò [something].) - This translates to "Okay, I really want to do [something] with you."
* 没问题,我很乐意和你一起做[something]. (Méi wèntí, wǒ hěn lèyì hé nǐ yīqǐ zuò [something].) - This translates to "No problem, I am very happy to do [something] with you."
Replace "[something]" with the specific thing you are making.
For example, if you are making a cake:
* 当然,我很乐意与您一起制作蛋糕。 (Dāngrán, wǒ hěn lèyì yǔ nín yīqǐ zhìzuò dàngāo.)
* 好呀,我很想和你一起做蛋糕。 (Hǎo ya, wǒ hěn xiǎng hé nǐ yīqǐ zuò dàngāo.)
Remember to choose the appropriate level of formality based on your relationship with the other person.