Hello Pamela,

I'm not an expert with spurr but maybe my idea can help. First fill a vial with only a little spurr. Let it polymerize and then lay your tube tube flat on top of this spurr layer. Add new spurr to cover the entire tube and again polymerize the spurr. After polymerisation you just saw out the block you need, rotate it to the correct position wright and glue it onto another spurrblock (for this mean I always use a superglue).

Succes!
leon