I recommend using a freight forwarder with an in-house customs broker, and if possible door-to-door air. FedEx or DHL would be good choices from China to the USA.
Yes - import duty is due but the actual fee may be zero depending on value and whether it is for personal use etc. There is a personal exemption ($1600) which can be used once per month and then a flat rate of 1.5% for the next $1000 and the remaining value is typically charged at 0.5-4.5% depending on the import code (trade classification). So if your laser is invoiced at $3600 and for personal use, you will likely pay $50 duty (non-medical laser).
If you get the size, weight and harmonized code you can talk to the freight companies and obtain quotes for shipping and duty.
If it is marked as a gift at a nominal value, then yes it can be seized. This would incur additional fees under the anti-dumping regulation which could include loss of the shipment.
The laser will also require the correct FDA certifications to be released, delays here can also incur significant fees.
Most reputable companies will be able to arrange this for you and often cheaper too. If they can't, walk... there are plenty of options.