Have looked through as many past threads on this subject as I could find.
Seems easy for 027 Track - I have already done it.
But for O Gauge tubular - not easy to find something affordable and suitable.
1. 3R Plastics ties - only available in 027 and also rubber or plastic - I would prefer wood
2. 1/4 x 3/4 in. x 96 in. Solid Pine Screen Molding (which can be cut narrower on a table saw) is NOT 1/4". That and lattice molding are actually 3/16 which is not thick enough.
3. Kappler Scale Lumber makes O Gauge ties, but those are even thinner
4. Northeast Scale Lumber sells bags of ties WITH NO THICKNESS specified. I wrote to them and asked, but they never responded.
5. Midwest Lumber 1/4 x 1/2 x 24 Basswood Strips # 4069. This LOOKS like it is 1/4" in the photos, but is out of stock everywhere and those who claim to have it don't respond to email inquiries.