This seems to be what you're aiming for:
# NOTE: If there are multiple NICs that match the wildcarded name in each Get-NetAdapter
# this will produce unexpected results!
[PSCustomObject]@{
Serial = (Get-WmiObject Win32_BIOS).SerialNumber
"PC Model" = (Get-WmiObject -Class:Win32_ComputerSystem).Model
Ethernet = (Get-NetAdapter -Name Ethernet*).MacAddress
WiFi = (Get-NetAdapter -Name Wi-Fi*).MacAddress
BlueTooth = (Get-NetAdapter -Name Bluetooth*).MacAddress
} | Export-Csv -Path C:\NICs.csv -notypeinformation