A first device and a second device can include at least one alignment feature and at least one corresponding constraint. The alignment feature and the constraint can be configured to align the first device and the second device when the alignment feature is inserted into the constraint. The alignment feature and the constraint can be further configured to direct relative movement between the first device and the second device due to relative thermal expansion or contraction between the first device and the second device. The directed relative movement can keep the first device and the second device aligned over a predetermined temperature range.