Which 105? The lever bracket is a listed spare, e.g. for ST-5700 right hand it's Y6TH98090, there are some in Germany on ebay https://www.ebay.co.uk/itm/394146011284
Thanks for taking the time to check their availability. Chunky price plus (post-Brexit) postage would have left me wondering until the above resolution became available.
I wonder if anyone is 3D printing the shells?
Not worth it, the OEM ones are available and cheap. The alternatives (buy second hand, buy new 4700, upgrade to 105 11-speed) are all better value than reverse engineering components of an obsolete groupset.
Which 105? The lever bracket is a listed spare, e.g. for ST-5700 right hand it's Y6TH98090, there are some in Germany on ebay https://www.ebay.co.uk/itm/394146011284