Polycarbonate (PC):

Pros: Excellent impact resistance, clarity, and good heat resistance.
Cons: More expensive than some other materials, susceptible to scratching, and can release Bisphenol A (BPA) under certain conditions.

Acrylic (PMMA):

Pros: Excellent clarity, affordable, and easy to machine.
Cons: Lower impact resistance than PC, susceptible to scratching, and not as heat resistant as PC.

Cyclic Olefin Copolymer (COC):

Pros: Excellent chemical resistance, clarity, and biocompatibility.
Cons: More expensive than PC or acrylic, and not as readily available.

Polybutylene Terephthalate (PBT):

Pros: Good clarity, chemical resistance, and heat resistance.
Cons: Lower impact resistance than PC, more expensive than acrylic, and can be brittle at low temperatures.

Polyethylene Terephthalate Glycol (PETG):

Pros: Good impact resistance, clarity, and chemical resistance.
Cons: Lower heat resistance than PC or PBT, and can be more difficult to machine than acrylic.

Cellulose Acetate (CA):

Pros: Good clarity, biodegradability, and can be easily dyed.
Cons: Lower impact resistance than other materials, susceptible to warping, and not as heat resistant as PC or PBT.

The best material for your clear parts will depend on your specific needs and priorities. Consider factors such as:

Required strength and impact resistance
Clarity and transparency
Heat resistance
Chemical resistance
Cost
Ease of processing
Environmental impact

By carefully considering these factors, you can choose the right material for your clear parts to ensure they meet your performance and aesthetic requirements.